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Acoustic cumulus: acoustic improvements in the graduate building science studio
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Content
Acoustic Cumulus
Acoustic Improvements in the Graduate Building Science Studio
By
Xiran Geng
A Thesis Presented to the
FACULTY OF THE USC SCHOOL OF ARCHITECTURE
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF BUILDING SCIENCE
May 2024
ii
ACKNOWLEDGMENTS
I would like to express my deepest gratitude to all those who contributed to the completion of my
thesis project. My thesis project could not have been achieved without their support, guidance
and encouragement.
First and foremost, I would like to express my sincere gratitude to my committee chair Douglas
E. Noble, and two committee members Elizabeth Valmont and Joon-Ho Choi for their invaluable
guidance, feedback, and support. Their expertise and patience have been instrumental in ensuring
the quality of my work.
I would also like to express my deepest gratitude to my family for their constant support and
encouragement during this project. Their love and inspiration have been invaluable, and I am
deeply thankful for having them in my life.
Committee chair:
Professor Douglas E. Noble, Ph.D., FAIA
USC, School of Architecture
Email: dnoble@usc.edu
Committee Member #2:
Professor Elizabeth Valmont, Ph.D.
USC, School of Architecture
Email: evalmont@usc.edu
Committee Member #3:
Professor Joon-Ho Choi, Ph.D.
USC, School of Architecture
Email: joonhoch@usc.edu
iii
TABLE OF CONTENTS
ACKNOWLEDGMENTS .............................................................................................................. ii
LIST OF TABLES......................................................................................................................... vi
LIST OF FIGURES ...................................................................................................................... vii
ABSTRACT................................................................................................................................... ix
KEYWORDS.................................................................................................................................. x
HYPOTHESIS................................................................................................................................ x
RESEARCH OBJECTIVES .......................................................................................................... xi
CHAPTER 1: INTRODUCTION................................................................................................... 1
1.1 Sound Principles and Key Terms.......................................................................................... 1
1.1.1 Sound Waves.................................................................................................................. 2
1.1.2 Sound Level.................................................................................................................... 4
1.1.3 Sound Reflection ............................................................................................................ 6
1.2 Room Acoustics .................................................................................................................... 7
1.2.1 Fundamental Concepts and Materials in Room Acoustics............................................. 8
1.2.2 Reverberation Time ...................................................................................................... 11
1.2.3 Speech Intelligibility..................................................................................................... 13
1.3 Acoustics Treatments.......................................................................................................... 14
1.3.1 Indoor and Outdoor Acoustic ....................................................................................... 14
1.3.2 Pattern of Reflected Sound........................................................................................... 15
1.4 About the Site...................................................................................................................... 17
1.4.1 History and Architecture .............................................................................................. 17
1.4.2 Purpose and Activities.................................................................................................. 18
1.4.3 Current Situation........................................................................................................... 19
1.5 Acoustic Software ............................................................................................................... 21
1.5.1 ODEON ........................................................................................................................ 21
1.6 Summary ............................................................................................................................. 23
CHAPTER 2: BACKGROUND AND LITERATURE REVIEW............................................... 24
2.1 Acoustic Challenges in Educational Environments............................................................ 24
2.1.1 Reverberation Time ...................................................................................................... 24
iv
2.1.2 Speech Intelligibility..................................................................................................... 26
2.2 Effects of Acoustic Quality on Attention and Efficiency ................................................... 27
2.3 Acoustic Design Principles ................................................................................................. 28
2.3.1 Design Strategies for Optimal Acoustics...................................................................... 28
2.3.2 Room Acoustic Materials............................................................................................. 29
2.4 Acoustic Software ODEON Simulation.............................................................................. 30
CHAPTER 3: METHODOLOGY................................................................................................ 31
3.1 Assessing the Acoustic Problems........................................................................................ 32
3.1.1 Qualitative Assessment................................................................................................. 32
3.1.2 Real-Life Quantitative Assessment .............................................................................. 33
3.1.3 Digital Quantitative Assessment .................................................................................. 35
3.2 Design Solutions and Alternatives...................................................................................... 37
3.3 Installation and Implementation.......................................................................................... 38
3.4 Testing................................................................................................................................. 39
3.5 Summary ............................................................................................................................. 40
CHAPTER 4: SIMULATION AND DATA................................................................................. 41
4.1 MBS Corner in Case Studies............................................................................................... 41
4.2 Acoustic Modelling of MBS Corner................................................................................... 43
4.2.1 Geometrical Modelling and Calibration....................................................................... 43
4.2.2 Simulation settings, sources, and receivers.................................................................. 45
4.2.3 Existing Room RT........................................................................................................ 47
4.2.4 Existing Room STI....................................................................................................... 50
4.3 Acoustic Element Design.................................................................................................... 53
4.3.1 Acoustic Element Design Strategy............................................................................... 53
4.3.2 Case Study #1 for Absorbing Material......................................................................... 54
4.3.2.1 Simulation settings................................................................................................. 54
4.3.2.2 Design Solutions and RT ....................................................................................... 55
4.3.2.3 STI.......................................................................................................................... 58
4.3.3 Case Study #2 for Reflecting Material ......................................................................... 60
4.3.3.1 Simulation settings................................................................................................. 60
4.3.3.2 Design Solutions and RT ....................................................................................... 61
v
4.3.3.3 STI.......................................................................................................................... 64
4.4 Data Analysis...................................................................................................................... 65
4.4.1 Case Study #1 ........................................................................................................... 65
4.4.2 Case Study #2 ........................................................................................................... 68
CHAPTER 5: INSTALLATION AND DATA ............................................................................ 72
5.1 Real-Life Existing Room RT Measurement........................................................................ 72
5.1.1 Equipment Setup and Calibration ............................................................................. 72
5.1.2 Classroom Preparation.............................................................................................. 75
5.1.3 Measurement Procedure............................................................................................ 76
5.1.4 Data Collection and Analysis.................................................................................... 79
5.2 Real Life Case Study #1 for Absorbing Material................................................................ 81
5.2.1 Design Solution 3D Construction Model.................................................................. 81
5.2.2 Supplies and Equipment Acquisition........................................................................ 83
5.2.3 Installation................................................................................................................. 84
5.2.4 Real-Life Testing and Data....................................................................................... 89
5.3 Real-Life Case Study #2 for Reflecting Material................................................................ 93
5.3.1 Design Solution 3D Construction Model.................................................................. 93
5.3.2 Supplies and Equipment Acquisition........................................................................ 94
5.3.3 Installation................................................................................................................. 94
5.3.4 Real-Life Testing and Data....................................................................................... 96
5.4 Summary ............................................................................................................................. 97
CHAPTER 6: CONCLUSION AND FUTURE WORK.............................................................. 98
6.1 Conclusion........................................................................................................................... 98
6.2 Future Work ........................................................................................................................ 98
6.2.1 Limitations of Current Work ........................................................................................ 99
6.3 Summary ........................................................................................................................... 100
BIBLIOGRAPHY....................................................................................................................... 101
vi
LIST OF TABLES
Table 1: Acoustic Software........................................................................................................... 21
Table 2: Absorption coefficients of materials in existing classrooms.......................................... 44
Table 3: Location of sound source and receivers.......................................................................... 45
Table 4: Existing room receivers 1 and 2 RT ............................................................................... 49
Table 5: Absorption coefficients of materials in classrooms (including acoustic element) ......... 55
Table 6: The Effect of Hanging Different Shapes of Acoustic Elements in the Classroom on RT
(Absorbing Material) .................................................................................................................... 56
Table 7:The Effect of Hanging Different Shapes of Acoustic Elements in the Classroom on STI
(Absorbing Material) .................................................................................................................... 58
Table 8: Absorption coefficients of materials in classrooms (including acoustic element) ......... 60
Table 9: The Effect of Hanging Different Shapes of Acoustic Elements in the Classroom on RT
(Reflecting Material)..................................................................................................................... 61
Table 10: The Effect of Hanging Different Shapes of Acoustic Elements in the Classroom on STI
(Reflecting Material)..................................................................................................................... 64
Table 11: Case study #1 RT (Absorbing material)....................................................................... 66
Table 12: Case study #2 RT (Reflecting material) ....................................................................... 68
Table 13: NTi 600-000-401 Exel Set Contents............................................................................. 74
Table 14: Real-Life Existing Room Receivers RT T(30)............................................................. 79
Table 15: Existing room real–life RT compare with ODEON RT............................................... 80
Table 16: Construction material list.............................................................................................. 83
Table 17: Real-Life Case Study #1 Receivers RT T(30).............................................................. 90
Table 18: Real-Life Vs. ODEON Case Study #1 RT ................................................................... 91
Table 19: Real-Life Case Study #2 Receivers RT T(30).............................................................. 96
Table 20: Real-Life Vs. ODEON Case Study #2 RT ................................................................... 96
vii
LIST OF FIGURES
Figure 1.0-1 Sound High-Frequency and Low-Frequency Diagram.............................................. 2
Figure 1.0-2 Hearing and Voicing Ranges Diagram ...................................................................... 3
Figure 1.0-3 Amplitude of Sound Diagram.................................................................................... 4
Figure 1.0-4 Noise Level Decibel Chart (Mounika, 2023)............................................................. 5
Figure 1.0-5 Reflection of Sound (Sushmanag, 2023) ................................................................... 6
Figure 1.0-6 Sound Reflection Diagram (Frank Leonard Walker, 2021)....................................... 8
Figure 1.0-7 Sound Absorption Diagram (Frank Leonard Walker, 2021) ..................................... 9
Figure 1.0-8 Sound diffusion Diagram (Frank Leonard Walker, 2021)....................................... 10
Figure 1.0-9 Different Room Ideal Reverberation Time Diagram (The Andrews Group, 2020). 12
Figure 1.0-10 Different Room STI Chart (Paschakis, 2023)........................................................ 13
Figure 1.0-11 Level Seating Outdoors (Egan, 2007).................................................................... 15
Figure 1.0-12 Level Seating Indoors (Egan, 2007) ...................................................................... 15
Figure 1.0-13 Flat Reflector (Egan, 2007).................................................................................... 16
Figure 1.0-14 Concave Reflector (Egan, 2007)............................................................................ 16
Figure 1.0-15 Convex Reflector (Egan, 2007).............................................................................. 17
Figure 1.0-16 Watt Hall in University of Southern California ..................................................... 18
Figure 1.0-17 USC Watt Hall MBS Corner Overview................................................................. 19
Figure 1.0-18 USC Watt Hall MBS Corner Ceiling and Conference Table................................. 20
Figure 1.0-19 USC Watt Hall MBS Corner Floor Plan and Sections........................................... 20
Figure 3.0-1 Methodology Diagram ............................................................................................. 31
Figure 3.0-2 Signal Chain............................................................................................................. 34
Figure 3.0-3 Workflow for ODEON Simulation (ODEON, 2023) .............................................. 36
Figure 4.0-1 USC Watt Hall MBS Corner Overview................................................................... 41
Figure 4.0-2 USC Watt Hall MBS Corner Ceiling and Conference Table................................... 42
Figure 4.0-3 USC Watt Hall MBS Corner Floor Plan.................................................................. 42
Figure 4.0-4 MBS Corner 3D Model in SketchUp....................................................................... 43
Figure 4.0-5 MBS Corner 3D Model Input In ODEON............................................................... 44
Figure 4.0-6 Sound Source and Receivers.................................................................................... 45
Figure 4.0-7 Impulse Response Length and Number of Late Rays.............................................. 46
Figure 4.0-8 Free Run Acoustic Leakage Test ............................................................................. 47
Figure 4.0-9 Job List..................................................................................................................... 48
Figure 4.0-10Existing Room T(30) from R1&R2 ........................................................................ 49
Figure 4.0-11 Define Grid............................................................................................................. 51
Figure 4.0-12 Existing Room STI from R1&R2 .......................................................................... 52
Figure 4.0-13 RT_T(30) for Absorbing Material ......................................................................... 67
Figure 4.0-14 Case Study #1 RT_T(30) 500Hz and 1000Hz ....................................................... 67
Figure 4.0-15Case Study #1 STI................................................................................................... 68
Figure 4.0-16 RT_T(30) for Reflecting Material.......................................................................... 70
viii
Figure 4.0-17 Case Study #2 RT_T(30) 500Hz and 1000Hz ....................................................... 70
Figure 4.0-18 Case Study #2 STI.................................................................................................. 71
Figure 5.0-1 NTi 600-000-401 Exel Set ....................................................................................... 73
Figure 5.0-2 NTi 600-000-401 Exel Set Contents........................................................................ 73
Figure 5.0-3 Acoustic Analyzer Assemble and Install ................................................................. 75
Figure 5.0-4 Classroom Set Up Plan ............................................................................................ 76
Figure 5.0-5 Balloon Pop RT Test................................................................................................ 77
Figure 5.0-6 Real-Life RT Test Setup .......................................................................................... 77
Figure 5.0-7 XL2 Equipment Setting Screenshot 1...................................................................... 78
Figure 5.0-8 XL2 Equipment Screenshot 2 .................................................................................. 79
Figure 5.0-9 Existing Room Real–Life RT Compare with ODEON RT...................................... 81
Figure 5.0-10 Case Study #1 Detailed Construction Drawings.................................................... 82
Figure 5.0-11 Case Study #1 Schematic Diagram of Construction Steps.................................... 82
Figure 5.0-12 Connecting Cardboard Extension to Wood Stud ................................................... 84
Figure 5.0-13 Foam Board after Applying the Sound-Absorbing Material.................................. 84
Figure 5.0-14 Cardboard Beams................................................................................................... 85
Figure 5.0-15 Fasten the Wood Stud to the Table Leg Using Zip Ties........................................ 86
Figure 5.0-16 Installing Wood Studs Overview ........................................................................... 86
Figure 5.0-17 Installing the Pre-made Cardboard Beam .............................................................. 87
Figure 5.0-18 Installing the Pre-made Cardboard Beam Overview ............................................. 87
Figure 5.0-19 Installing Foam Board............................................................................................ 88
Figure 5.0-20 Final Installation View........................................................................................... 89
Figure 5.0-21 During Case Study #1 Real-Life Testing............................................................... 90
Figure 5.0-22 Case Study #1 Real-Life Testing Overview........................................................... 91
Figure 5.0-23 Real-Life Vs. ODEON Case Study #1 RT............................................................. 92
Figure 5.0-24 Case Study #2 Detailed Construction Drawings.................................................... 93
Figure 5.0-25 Case Study #2 Schematic Diagram of Construction Steps.................................... 93
Figure 5.0-26 Case Study #2 Final Installation View................................................................... 95
Figure 5.0-27 Case Study #2 Real-Life RT .................................................................................. 96
ix
ABSTRACT
In the realm of acoustics, the scientific exploration of sound and its transmission, sound waves,
characterized by vibrational energy, possess the capacity to transmit data, elicit emotional
responses, and impact human wellness. This investigation delves into the paramount issue of
architectural acoustics within the educational institution's open studio environment, especially
focusing on the conference area. The open studio functions as an intricate area accommodating
diverse concurrent activities including academic programs, individual study, collective
discussions, Zoom meetings, etc. The distinct characteristics of these activities necessitate
varying acoustic environments. For instance, lecture sessions demand a tranquil ambiance. This
dissertation addresses acoustical challenges observed in the Master of Building Science Corner
of the 3rd floor of Watt Hall at the University of Southern California. Introducing a design and
deployment strategy for an acoustic apparatus aimed at curtailing reverberation time and
enhancing speech intelligibility. The objective centers around refining spatial regulation,
facilitating effective communication, and augmenting the overall user experience. For acoustical
assessment, the Odeon software was employed to develop a sophisticated analytical model.
x
KEYWORDS
Building Science, Room Acoustic, Reverbration Time, Speech Intelligibility
HYPOTHESIS
Designing an innovative acoustic element above the Watt Hall MBS corner can effectively
reduce reverberation time and enhance speech intelligibility; resulting in improved room control,
communication, and overall user experience.
xi
RESEARCH OBJECTIVES
● Developed and innovated acoustic components to reduce reverberation time and improve
speech intelligibility in MBS Corner’s open studio meeting areas.
● Created and analyzed complex acoustic models of open studio areas using Odeon
software designed to evaluate and optimize the acoustic environment for a wide range of
activities such as lectures, conferences and individual learning.
1
CHAPTER 1: INTRODUCTION
The importance of classroom and teaching area acoustics cannot be overemphasized, as it has a
direct impact on the effectiveness of teaching and the learning experience of students. Good
acoustic design ensures that students clearly hear and understand what is being said, which is
essential for concentration, comprehension and cognitive development. In environments with
poor acoustics, students may find it difficult to hear the teacher's voice, which can lead to
reduced engagement, increased frustration, and lower academic achievement. This is particularly
important for younger students, who are more susceptible to the negative effects of background
noise and reverberation.
The nature of the problem is the acoustic problems in USC Watt Hall third floor MBS corner.
The space has a bad condition on acoustic and because different activities are going on in a day.
This chapter will provide an introduction to the fundamental aspects of sound and room
acoustics. It will cover sound principles and key terms, room acoustics, acoustics treatments, site
information and acoustic software.
1.1 Sound Principles and Key Terms
Sound principles are the fundamental concepts and guidelines related to the physics and
perception of sound. These concepts are important in the study of sound production,
transmission, and perception and are relevant to the disciplines of physics, acoustics,
engineering, and music. The importance of these principles and concepts lies in their ability to
enhance the understanding of the site's acoustic conditions. Studying acoustics on the third floor
2
of Watt Hall, the important features of acoustics including sound waves, sound level and the
ability of sound reflection.
1.1.1 Sound Waves
Sound waves are a type of mechanical wave, generated by the back-and-forth vibration of
particles of the medium in which they move. Sound waves require a medium, which can be solid,
liquid, or gas. (Zola, 2022)
Frequency, sometimes called pitch, is the number of times a sound pressure wave repeats per
second. (National Park Service, 2018) The lower the frequency, the fewer the oscillations.
Higher frequencies produce more oscillations. (Figure 1.0-1)
Figure 1.0-1 Sound High-Frequency and Low-Frequency Diagram
https://afsharphysics.wordpress.com/optics/optics-part-1-introduction-to-waves/sound/
3
The unit of frequency is called hertz (Hz). A person with normal hearing can hear sounds
between 20 Hz and 20,000 Hz. (Figure 1.0-2) Frequencies above 20,000 Hz are called ultrasonic.
Frequencies below 20 Hz are called infrasound. (National Park Service, 2018) Bats have the
highest hearing frequency of all mammals, up to 120,000 Hz. They use ultrasound as sonar to
avoid hitting obstacles. Elephants use infrasound to communicate, making sounds too low for
humans to hear. Because low-frequency sounds travel farther than high-frequency sounds,
infrasound is well-suited for long-distance communication. (National Park Service, 2018)
Figure 1.0-2 Hearing and Voicing Ranges Diagram
https://theory.labster.com/hearing-range-dbs/
The amplitude of a sound is related to the height of the wave. (Figure 1.0-3) It also corresponds
to loudness or volume. Loudness is directly proportional to the amplitude of the sound. The
4
greater the amplitude of a sound wave, the louder the sound will be. If the amplitude is small, the
sound will be weak. (Admin, 2023) Amplitude is measured in decibels (dB). The lower threshold
of human hearing is 0 dB at 1kHz. (National Parks Service, 2018) Since decibels are measured
on a logarithmic scale, a rise of 10 dB results in a tenfold increase in sound level, which is
equivalent to a doubling of perceived loudness. (Crocker, 1997) For example, if one hair dryer is
80 decibels, then 90 decibels is equivalent to the sound of 10 hair dryers.
Figure 1.0-3 Amplitude of Sound Diagram
https://byjus.com/physics/amplitude-frequency-period-sound/
1.1.2 Sound Level
Sound, in the realm of acoustics, is characterized by several parameters that provide insight into
its intensity, energy, and the way it interacts with the environment. The Sound Power Level
(SWL) and Sound Pressure Level (SPL) are two key metrics among these parameters.
The Sound Power Level and Sound Pressure Level are both measured in decibels. Sound Power
is always higher than the Sound Pressure. Sound Pressure Level is what you will ultimately hear.
(EcoAir, 2020)
5
The sound or noise measurement is known as Sound Pressure Level or SPL. (Mounika, 2023)
For example, in the case of an industrial machine, although the sound power level remains
constant, the sound pressure level measured next to the machine will be different from the sound
pressure level measured 10 meters away. In addition, if the machine is placed in an echo
chamber rather than in an open field, the sound pressure level at a given distance will vary due to
the effects of reflection and absorption in the environment. The Noise Level Decibel Chart
shows some of the common sounds or noises encountered and their effect on our ears. Any noise
above 85 decibels is loud and harmful to the ears. (Figure 1.0-4)
Figure 1.0-4 Noise Level Decibel Chart (Mounika, 2023)
https://www.electronicshub.org/noise-level-decibels-chart/
6
The sound power level is a measurement of the sound level produced by the appliance when it is
turned on, without taking any consideration of any specific room-related conditions. (EcoAir,
2020) This value is usually provided on the energy label that comes with the appliance.
1.1.3 Sound Reflection
Sound reflection is the phenomenon of sound hitting an obstacle and reflecting back in the same
medium. Sound travels through mediums such as solids, liquids, and gases. Unlike other waves
such as light waves, sound cannot travel in a vacuum; it needs a medium to travel. (Sushmanag,
2023) A simple example of this is when people speak in an empty hall and hear an echo. This is
produced by the reflection of sound.
Figure 1.0-5 Reflection of Sound (Sushmanag, 2023)
https://www.geeksforgeeks.org/reflection-of-sound/
7
There are two laws of reflection of sound:
1. The angle of reflection of the sound wave is always equal to the angle of incidence of the
sound wave. Angle of Reflection = Angle of Incidence (Sushmanag, 2023) (Figure 1.0-5)
2. For sound waves, the incident wave, the reflected wave, and the normal at the point of
incidence lie on the same plane. (Sushmanag, 2023) In Figure 1.5 the sound is reflected
on the wood bar which has been highlighted in red.
1.2 Room Acoustics
Interior acoustics involves the study of sound behavior in enclosed spaces. The discipline studies
how sound waves interact with room boundaries (such as walls, ceilings, and floors) as well as
objects within the room. The sound quality of any space, whether a spacious concert hall or a
classroom, is greatly affected by these interactions. Factors such as reflection, absorption, and
diffusion play a key role in shaping the acoustic properties of a room. (McIver, 2023)
Understanding room acoustics is essential to optimizing sound quality, enhancing musical
performances, ensuring clear voice communication, and creating comfortable living and working
environments.
8
1.2.1 Fundamental Concepts and Materials in Room Acoustics
Figure 1.0-6 Sound Reflection Diagram (Frank Leonard Walker, 2021)
https://www.frankleonardwalker.com/post/19-a-reflection-rear-wall-diffusion
Sound reflection occurs when a sound wave encounters a boundary or surface and reflects back
to the original medium, rather than traveling through or being absorbed by the boundary.
(Netwell, 2021) It is like the reflection of light from a mirror. (Figure 1.0-6)
Factors affecting reflection include the angle of incidence of the sound. The angle at which a
sound wave strikes a surface affects the direction of the reflected sound. The law of reflection
states that the angle of incidence equals the angle of reflection. (Sushmanag, 2023) Different
surface materials and textures have different effects on the reflection of sound. Hard, flat, and
smooth surfaces (such as concrete or glass) tend to reflect sound more effectively than soft,
irregular surfaces. In architectural design, acoustically reflective materials are often used.
concrete, marble floors, glass and hardwood. (Materials and sound, 2009)This type of material
bounces sound waves back into the original space and continues to reflect around the space.
9
Figure 1.0-7 Sound Absorption Diagram (Frank Leonard Walker, 2021)
https://www.frankleonardwalker.com/post/19-a-reflection-rear-wall-diffusion
Sound absorption is the phenomenon whereby a material absorbs sound energy and converts it
into another form of energy, usually heat. Absorbing materials reduce the amplitude of reflected
sound waves. (McIver, 2023) These materials reduce the intensity of sound and are essential for
controlling reverberation. (Figure 1.0-7)
Material porosity, material thickness, and density are all factors that affect sound absorption.
Porous materials, such as open-cell foams or fabrics, allow sound waves to enter their structure,
dissipating the energy as it passes through the material. (SemiColonWeb, 2020) Thicker
materials have better absorption, especially for lower frequencies. Sound-absorbing materials are
essential for controlling reverberation and reducing ambient noise levels in spaces such as
recording studios, theaters, classrooms, or offices.
10
Figure 1.0-8 Sound diffusion Diagram (Frank Leonard Walker, 2021)
https://www.frankleonardwalker.com/post/19-a-reflection-rear-wall-diffusion
Instead of reflecting sound in a single direction, diffusing surfaces scatter sound in multiple
directions, creating a more uniform sound field. (Figure 1.0-8) Factors that affect sound diffusion
include the surface geometry of the material as well as its hardness. Irregular, uneven surfaces
cause sound waves to scatter in different directions. The more varied and complex the surface,
the better it usually diffuses sound. When properly shaped, hard materials can reflect sound more
effectively in all directions. Adding diffusion retains enough energy in the room to make the
sound sound more natural, while dispersing some of the reflected energy. (AcousticalSurfaces,
2023)
11
1.2.2 Reverberation Time
Reverberation time is the amount of time that passes before the sound fades away from its source
after it has stopped. (Larson Davis, 2022) One objective way to quantify reverberation is with the
metric Reverberation Time 60 (RT60). The duration of time it takes for the sound pressure level
to drop by 60 dB following the cessation of the source is known as the RT60. (Larson Davis,
2022) Acoustically, areas that have an RT60 of less than 0.3 seconds are regarded as "dead,"
whereas those that have an RT60 of more than 2 seconds are regarded as "echoic." (The Andrews
Group, 2020) A longer reverb time will result in a room sounding echoed and full. A short reverb
time is the opposite and may make the room sound dull or dry. (The Andrews Group, 2020)
In order to measure the RT60, the room must first be filled with sound. This can be done by
poking a balloon or using another sound source. The source needs to hit every frequency from
low to high to ensure the integrity of the information. A sound level meter measures the time it
takes for the sound level to decay and reports the results. (Larson Davis, 2022) Putting enough
sound into a room to measure RT60 directly and completely is a difficult task, so it is now
common to use only a fraction of the sound decay to infer it. If we measure the time when the
SPL decays by 20 dB and multiply it by 3, this reverberation time is called the T20
measurement. If you measure the time when the SPL decays by 30 dB and multiply it by 2, this
is called a T30 measurement. In both cases, the measurement starts after the first 5 dB of decay.
(Larson Davis, 2022) T20 is a suitable method for measuring reverberation time when the
maximum sound intensity is 35 dB or more above the background noise level. T30 is a suitable
method for measuring reverberation time when the highest sound intensity is 45 dB or more
above the background noise level. (Larson Davis, 2022)
12
Figure 1.0-9 Different Room Ideal Reverberation Time Diagram (The Andrews Group, 2020)
https://theandrewsgroup.com.au/what-to-measure/
The ideal reverberation time depends on the intended use of the space. For example, theatres and
auditoriums require longer reverberation times (usually more than 1.4 seconds) to enhance
musical performance. In comparison, libraries or recording studios may aim for shorter times
(less than 1 second) for clarity. The ideal reverberation time for a classroom will be under 0.9s.
(Figure 1.0-9) Adjusting the reverberation time to the specific room function ensures that
optimum acoustics are achieved.
13
1.2.3 Speech Intelligibility
Speech intelligibility is the percentage of how well the listener is able to understand and
comprehend spoken words. (McMahon, 2017) For example, if you can only understand half of
what your child is saying, their speech intelligibility rating would be 50%. In terms of room
acoustics, ensuring optimal speech intelligibility is critical in environments such as classrooms,
auditoriums, and conference rooms, where effective communication is essential.
A variety of methods and metrics are used to measure speech intelligibility. The Speech
Transmission Index (STI) is a numerical value that quantifies the effect of the transmission
channel on the intelligibility of a message addressed to a listener. (Paschakis, 2023) The method
does not take into account the speaker or listener, but only objectively reflects how the
transmission channel affects speech intelligibility. It is calculated from the modulation changes
in the test signal and gives a value between 0 and 1, where 1 is the easiest to understand and 0 is
the hardest to understand. (Paschakis, 2023) Different room functions also have diverse ideal
STIs. (Figure 1.0-10)
Figure 1.0-10 Different Room STI Chart (Paschakis, 2023)
https://xiengineering.com/speech-intelligibility-index-sti-stipa-speech-intelligibilitymeasurements/
14
The percentage of all speech information that is audible to the listener for a certain speech
material is known as the speech intelligibility index, or SII. (Kringlebotn, 1999) SII varies in the
range 0-1. A higher index value indicates better intelligibility. This method is suitable for
assessing hearing impairment.
1.3 Acoustics Treatments
Acoustic treatments are important interventions aimed at controlling and improving the acoustic
properties of indoor or outdoor environments. Indoor acoustic treatments focus on optimizing
sound quality in enclosed spaces such as classrooms and offices by managing sound reflections,
reducing reverberation and controlling noise levels. Patterns of reflected sound are an important
aspect of room acoustics, dealing with the direction and behavior of sound waves as they reflect
off surfaces. Managing these reflections correctly can go a long way towards achieving a
balanced sound distribution and preventing problems such as echo and feedback. Spaces that
support health, communication and performance can be created through thoughtful acoustical
treatments that consider the unique characteristics of the environment.
1.3.1 Indoor and Outdoor Acoustic
During outdoor lectures or speeches, audiences primarily perceive direct sound rather than
reflected sound. As the sound propagates, its intensity diminishes, potentially resulting in
reduced audibility for individuals situated at greater distances, such as those seated at the back.
(Figure 1.0-11)
15
Figure 1.0-11 Level Seating Outdoors (Egan, 2007)
The ceiling within an enclosed space serves as a potential reflective surface for sound waves.
The sound may undergo one or multiple reflections before reaching an individual's auditory
perception. This phenomenon facilitates individuals seated in distant rows, such as the rear, to
receive sound via these reflected paths. (Figure 1.0-12)
Figure 1.0-12 Level Seating Indoors (Egan, 2007)
1.3.2 Pattern of Reflected Sound
The distribution of reflected sound is followed by a list of the concave, flat, and convex soundreflecting surfaces in increasing order of sound dispersal impact. (Egan, 2007)The shading in the
figure indicates the distribution of reflected acoustic energy from an equal-length reflector.
16
Building components with a flat, hard surface that is large enough and situated correctly at an
angle can transfer reflected sound efficiently. (Figure 1.0-13) (Egan, 2007)
Figure 1.0-13 Flat Reflector (Egan, 2007)
Concave surfaces can focus sound, creating hot spots and echoes in the audience area. They are
also poor transmitters of sound energy, so concave surfaces should be avoided where soundreflecting surfaces are needed, such as near lecterns or auditoriums. (Figure 1.0-14) (Egan, 2007)
Figure 1.0-14 Concave Reflector (Egan, 2007)
When a convex reflector is large enough and with a hard reflective surface, it can be the most
efficient form of sound propagation. It disperses the sound and enhances the diffusion effect,
which is ideal for music appreciation (Figure 1.0-15). (Egan, 2007) The sound energy reflected
by a convex surface is more evenly distributed over a wide frequency range.
17
Figure 1.0-15 Convex Reflector (Egan, 2007)
1.4 About the Site
1.4.1 History and Architecture
Watt Hall is the headquarters for the USC School of Architecture and the USC Roski School of
Art and Design. Watt Hall was named in honor of Ray and Nadine Watt, prominent real estate
developers and benefactors of USC. The original building had two floors plus a basement and
Matt Construction added a third floor of approximately 22,500 square feet to the building at a
later date. The design architect for the 3rd floor was Christoph Kapeller.
Watt Hall combines functionality and aesthetics (Figure 1.0-16). The exterior incorporates
geometric shapes, large windows that allow natural light to penetrate the interior.
18
Figure 1.0-16 Watt Hall in University of Southern California
https://www.researchgate.net/figure/15-The-exterior-of-Watt-Hall_fig10_235776067
1.4.2 Purpose and Activities
In Watt Hall, activities predominantly focus on architectural design and its associated disciplines.
Many students are allocated individual workstations within the studio, facilitating endeavors
such as self-study, three-dimensional modeling, and related academic tasks. Periodically, the hall
or its affiliated gallery spaces host exhibitions where students display their projects, designs, or
artworks. The facility regularly conducts workshops and seminars, with flexible spaces on the
second and third floors adaptable to varied functions. Furthermore, esteemed professionals from
architecture, fine arts, and design frequently deliver lectures. Collaborative efforts are also
emphasized, with students often engaging in group discussions to complete assignments.
The site studied is the Watt Hall Master Building Science Corner. (Figure1.16) It is located in the
corner of the third-floor open-plan studio. Lectures and student discussions are the most common
activities in this area.
19
1.4.3 Current Situation
Based on both visual and auditory analyses conducted in the MBS corner, the space exhibits
several distinct architectural and acoustic characteristics. Architecturally, the room boasts a high
ceiling, expansive area, and open floor design, and is constructed primarily of hard materials,
including concrete, steel, and glass. (Figure1.0-17) Acoustically, due to the high reflectivity of
the materials, it can be inferred that the room possesses significant reverberation properties.
Throughout daylight hours, as activities intensify with both students and faculty engaging in
various endeavors, there is an observable increase in sound levels. This amplification in sound
forces individuals to elevate their vocal projection to ensure audibility. This phenomenon is
reminiscent of the "cocktail party effect," which refers to the human capacity to concentrate on a
single auditory stimulus amidst a backdrop of competing noises. Notably, there seems to be a
deficiency in sound isolation within this space, resulting in considerable noise intrusion from
adjacent areas. (Figure1.0-18) Ambient noise from mechanical utilities and HVAC systems,
however, remains relatively inconspicuous. (Figure1.0-19)
Figure 1.0-17 USC Watt Hall MBS Corner Overview
20
Figure 1.0-18 USC Watt Hall MBS Corner Ceiling and Conference Table
Figure 1.0-19 USC Watt Hall MBS Corner Floor Plan and Sections
21
1.5 Acoustic Software
Table 1: Acoustic Software
Name Description Specificities Website
ODEON A comprehensive software for
room acoustic simulations and
auralizations.
- Professional analysis for
all kinds of spaces (from
bathrooms to concert
halls)
- Learning curve for
advanced features
- Good auralization
capabilities
https://odeon.dk/
EASE A software for designing and
analyzing acoustics and sound
systems in 3D environments.
- Detailed acoustic
modeling
- Strong electro-acoustic
prediction
- Integration with 3D
modeling tools
https://www.afmg.eu/
en/ease
CATT A room acoustic prediction
software that uses the imagesource method and raytracing.
- TUCT interface is
efficient
- Auralization capabilities
https://www.catt.se/
Room EQ Wizard
(REW)
A software tool for measuring
and analyzing room and
loudspeaker responses.
- Simple interface with
detailed results
- Limited to room and
speaker calibrations
https://www.roomeqw
izard.com/
This section describes different acoustic software, including ODEON, EASE, CATT, and REW.
Based on the above analysis, the project will use ODEON as the acoustic analysis software.
(Table 1)
1.5.1 ODEON
ODEON was chosen as the acoustic analysis software for the project. Designed to facilitate the
analysis and design of acoustic environments, ODEON integrates sophisticated algorithms and a
user-friendly interface to simulate and predict the acoustic properties of enclosed spaces from
small rooms to large concert halls.
22
Using image-source modeling in conjunction with the ray-tracing technique is one of ODEON's
primary features. The precise modeling of sound propagation in three-dimensional spaces is
made possible by this hybrid technique. Ray tracing is an optical engineering technique that
tracks the course of sound waves as they scatter, absorb, or reflect off different surfaces. This
approach works especially well for forecasting sound energy distributions and comprehending
the behavior of sound in intricate architectural settings.
ODEON also offers a range of tools for measuring and analyzing room acoustic parameters, such
as reverberation time (RT), Speech Transmission Index (STI), and clarity. These parameters are
crucial for assessing the acoustic quality of a space. For instance, in a concert hall, a longer
reverberation time might be desirable for classical music, whereas in a lecture hall, clarity and
speech intelligibility take precedence.
Furthermore, the software's ability to model complex geometries and materials allows for
detailed acoustic analysis. This feature is particularly beneficial in the early stages of
architectural design, where modifications to shape, size, and material choices can significantly
impact the acoustic outcome.
The software also incorporates advanced auralization techniques. Auralization is the process of
creating audible sound files from data that represent the sound field in a simulated space. This
feature enables acoustic engineers and architects to not only visualize but also listen to the sound
in a simulated environment before it is physically built. This aspect of ODEON is invaluable for
concert hall design, where the aural experience is as critical as the visual aesthetics.
23
In the academic context, ODEON serves as an educational tool, assisting students in
understanding the principles of room acoustics. It provides a practical, hands-on experience in
acoustic analysis, which is crucial for students in acoustics and architecture programs.
1.6 Summary
The critical role of acoustics in the classroom and teaching field is undeniable and directly
impacts the effectiveness of instruction and the student learning experience. Poor acoustics,
especially in spaces such as the MBS corner on the third floor of USC's Watt Hall, can hinder
student engagement and understanding due to the noisy environment created by various
activities. This chapter aims to address these challenges by presenting basic sound principles,
room acoustics, acoustic treatments, and related software to provide a comprehensive approach
to understanding and improving acoustic conditions in educational spaces.
24
CHAPTER 2: BACKGROUND AND LITERATURE REVIEW
2.1 Acoustic Challenges in Educational Environments
The importance of acoustics in learning spaces is a critical yet often overlooked aspect of
educational environments. An educational space's acoustics should promote learning by allowing
necessary sound to be transmitted and preventing undesirable noise. (Pääkkönen, Vehviläinen
and Jokitulppo, 2015) Poor acoustic conditions in classrooms can negatively affect students'
ability to hear and understand speech, impacting their ability to learn and communicate
effectively. This chapter is about reverberation time, speech intelligibility, the impact of acoustic
quality on attention, overall well-being and comfort, long-term academic outcomes, and
technology and multimedia.
2.1.1 Reverberation Time
Room acoustic reverberation time is an important parameter for assessing the acoustic quality of
a room. In order to understand the reverberation time in different acoustic environments, various
studies have been conducted to simulate and measure the impulse response of rooms. Antweiler
focused on modeling time-varying room impulse responses (C. Antweiler and H.-G. Symanzik,
2002), while Botteldooren used finite-difference time-domain simulations to study low and
medium frequency room acoustics. (Botteldooren, 1995)
Cirillo et al. studied the acoustics of Romanesque churches in Apulia and found correlations
between architectural and acoustic parameters, emphasizing in particular the relationship
between reverberation time and total sound absorption. (Cirillo and Martellotta, 2003) Keränen
et al. compared simple indoor acoustic models of industrial spaces, emphasizing the challenges
25
posed by time-consuming model creation and calculations in preliminary indoor acoustic design.
(Keränen and Hongisto, 2010)
Jeong et al. addressed the problem of low-frequency artifacts in finite-difference time-domain
room acoustic simulations and proposed a source implementation to eliminate these effects. They
also introduced the concept of slope for determining transition times and quantifying the field
performance of diffusers, providing an objective measure for detecting acoustic defects. (Jeong
and Yiu Wai Lam, 2012)
Nowoświat et al. explored the effect of acoustic remedies on altering reverberation times at
different frequencies in domes used for worship, emphasizing the importance of acoustic
measurement methods in assessing sound reverberation. (Nowoświat, Olechowska and
Marchacz, 2020)
Pind et al. performed time-domain acoustic simulations of rooms with extended-response porous
absorbers using the discontinuous Galerkin method, highlighting the potential errors that can
arise from the use of certain approximations when modeling room acoustic parameters. (Pind et
al., 2020)
In summary, these studies demonstrate the importance of accurate indoor acoustic simulations
and measurements for understanding reverberation times and improving acoustic quality in a
variety of environments.
26
2.1.2 Speech Intelligibility
Speech intelligibility in room acoustics is a key factor that can have a significant impact on the
quality of verbal communication. Various indices such as the Speech Transmission Index (STI)
and the Rapid Speech Transmission Index (RASTI) have been developed for evaluating speech
intelligibility, taking into account room reverberation and background noise levels. (Tang and
Yeung, 2004) Acoustic adjustment of classrooms improves speech intelligibility, and after
acoustic adjustment, STI can be improved from a satisfactory level to an excellent level.
(Mikulski, 2013)
However, room acoustic conditions also affect speech intelligibility, which varies between
languages such as English, Polish, Arabic and Mandarin. (Galbrun and Kitapci, 2016) Factors
such as room size and content can affect acoustics and speech intelligibility; the larger the room,
the longer the sound reverberation time, which may negatively affect intelligibility. (McNeer et
al., 2017) Studies have also examined the relationship between speech intelligibility tests and
STIs in classrooms with different acoustic conditions, highlighting the importance of considering
the acoustic characteristics of the classroom when assessing speech intelligibility. (Radosz,
2023)
Perceptual analyses of speech intelligibility in multilingual environments showed differences in
perceived speech intelligibility compared to objective tests, suggesting the complexity of
assessing speech intelligibility across languages. (Kitapci and Galbrun, 2019) Furthermore,
studies comparing speech intelligibility in real and virtual sound environments have shown that
27
virtual reproductions using microphone arrays are very close to the speech intelligibility
measured in the reference room. (Ahrens, Marschall and Dau, 2019)
In conclusion, research on indoor acoustic speech intelligibility emphasizes the importance of
considering factors such as room size, acoustic adaptation, language differences, and virtual
sound environments when assessing and improving speech intelligibility for effective verbal
communication. (Mikulski, 2019)
2.2 Effects of Acoustic Quality on Attention and Efficiency
The effect of sound quality on efficiency has been studied in a variety of contexts. Studies on the
impact of noise on people's productivity have shown mixed results. Bang et al. found that higher
sensory noise actually improves metacognitive efficiency, which goes against general intuition.
(Bang, Shekhar and Rahnev, 2019) On the other hand, Hockey discusses how high noise levels
can affect human productivity, with extroverts being more susceptible to noise-induced
narrowing of attention span. (Hockey, 1972)
Several studies have examined the effects of noise on student efficiency and academic
performance. Room noise and reverberation in classroom environments are associated with
poorer verbalization in children. (Klatte, Bergström and Lachmann, 2013) Some studies have
shown that noise can improve academic performance, especially for people who are sleep
deprived, as it increases their arousal. (Jafari et al., 2019) However, background noise, especially
speech noise, has been shown to reduce academic performance. (Braat-Eggen et al., 2021)
Excessive noise in the classroom reduces a child's ability to hear the lesson and negatively
affects the child's ability to learn. (Knauf Insulation North America, 2024) Previous studies have
28
shown that noise can have a negative impact on children's performance in school, including
reduced memory, motivation and reading ability. (Shield and Dockrell, 2008) Noisy classrooms
are known to have a negative impact on students' listening performance. (Caviola et al., 2021) In
addition, background white noise has been shown to affect the memory of inattentive
schoolchildren, which may affect their efficiency in completing high workload tasks. (Söderlund
et al., 2010) Overall, noise pollution has a negative impact on students' academic performance,
with an increase in the number of noise days associated with a decrease in academic efficiency
and learning outcomes. These findings underscore the importance of creating quiet and
conducive learning environments to optimize student efficiency and achievement.
2.3 Acoustic Design Principles
2.3.1 Design Strategies for Optimal Acoustics
The literature on optimized acoustic design strategies covers a wide range of topics and
approaches. Habbal explores the problem of optimizing the design of non-smooth shapes in
linear acoustics, emphasizing the sensitivity of acoustic pressure to shape changes at different
frequencies. (Habbal, 1998) Whitmer et al. focused on redesigning flat plates to improve
transmission losses between shells through passive and active structural tailoring. Future
research directions include modal clustering and transfer strategies. (Whitmer and Kelkar, 2006)
Sheng discusses the optimal sound absorption structure, showing a structure with a nearly perfect
flat sound absorption spectrum. (Sheng, 2017) All of these studies provide valuable insights and
methods for the field of optimal acoustic design.
29
2.3.2 Room Acoustic Materials
Room acoustic materials play a crucial role in determining the sound absorption and overall
acoustic quality of a space. Various studies have been conducted to explore different aspects of
room acoustics and the effect of materials on sound transmission. The importance of
understanding how materials affect sound absorption in enclosed spaces was emphasized by
Nascimento et al.'s study of sound absorption in scale-modeled reverberant chambers.
(Nascimento, Moyses Zindeluk and Silveira, 2002) Similarly, Escolano et al. proposed a new
approach to modeling fibrous materials using the finite-difference time-domain method,
emphasizing the need for accurate modeling of materials in acoustic problems. (José Escolano
and Basilio Pueo, 2007)
Citherlet et al. extended the functionality of a building simulation application to support the
assessment of indoor acoustics, demonstrating the importance of considering acoustics alongside
other building performance metrics. (Citherlet and Hand, 2002)
In addition, Siltanen et al. presented the room acoustic rendering equation, a generalized integral
equation for modeling room acoustic parameters, demonstrating the complexity of modeling
acoustics in different spaces. (Siltanen et al., 2007)
Choi investigated the effect of diffusers on classroom acoustics and proposed the optimal
combination of acoustic absorption and diffusion materials to improve acoustics. (Choi, 2013)
Pelzer et al. developed a framework for real-time simulation and auralization of modifiable
rooms that allows users to interactively study the effects of changes on room acoustics. (Pelzer et
al., 2014) In addition, Zohra focuses on assessing the acoustic quality of worship spaces by
30
evaluating reverberation times, emphasizing the importance of using numerical simulation tools
for accurate assessment. (Benmaghsoula Zohra, 2016)
In summary, the literature on materials for indoor acoustics emphasizes the importance of
understanding how different materials affect the sound absorption and overall acoustic quality of
different spaces. By utilizing advanced modeling techniques and simulation tools, researchers
and designers can optimize indoor acoustics, thereby improving acoustic quality and occupant
comfort.
2.4 Acoustic Software ODEON Simulation
Computer modeling using Odeon acoustic prediction software highlighted the lack of acoustic
performance standards for educational facilities in Egypt by Awad et al. (Awad et al., 2012) Zhu
et al. compared simulated and field-measured speech intelligibility and showed that acoustic
simulation using ODEON software accurately predicted STI. (Zhu et al., 2015) Ciaburro et al.
used the Odeon software to evaluate the acoustic characteristics of the Odea of Pompeii and
Posillipo, showing its suitability for music, song and speech. (Ciaburro et al., 2020)
31
CHAPTER 3: METHODOLOGY
This chapter describes the comprehensive methodology used to address the acoustical challenges
identified in Watt Hall's MBS corner. The specific research methodology is divided into
accessing the acoustic problem, design alternatives, installation implementation, and testing.
(Figure3.0-1)
Figure 3.0-1 Methodology Diagram
32
3.1 Assessing the Acoustic Problems
Evaluating the acoustical problems of Watt Hall MBS will be divided into two major sections,
qualitative analysis and quantitative analysis. The qualitative analysis will be based on a
questionnaire administered to students and teachers who use MBS Corner daily. The quantitative
assessment will be a physical test on RT and STI to understand how sound will be performed in
the space.
3.1.1 Qualitative Assessment
The student-led assessment of Watt Hall's MBS corner extends to a comprehensive evaluation
that not only encompasses the physical and acoustic properties but also delves into the functional
and experiential aspects of the environment from a user perspective. The survey, aimed at
capturing the nuanced experiences of the students, will also inquire about the frequency of
disturbances encountered, allowing for a temporal dimension to the analysis of noise sources.
This will help to distinguish between constant and intermittent noise disruptions, providing a
clearer picture of the acoustic environment's dynamics.
In addition to rating noise sources, the survey will seek feedback on the effectiveness of
soundproofing between classrooms/meeting rooms and adjacent areas, including corridors, other
classrooms, and the external environment. This will assess the adequacy of current
soundproofing measures and identify areas for improvement.
To gain insight into potential solutions, the survey will also encourage students to suggest
improvements or changes that they believe would enhance the acoustic quality of the space. This
33
could include suggestions for physical alterations, changes to room use policies, or the
introduction of noise management practices.
The final results of this investigation will reflect the lived experiences of the students and
provide a solid foundation for subsequent analysis and intervention. The results of the study will
be synthesized into a report highlighting key issues and recommending actionable strategies to
optimize the acoustic environment in the MBS corner of Watt Hall. This approach ensures that
interventions are not only technically sound but also tailored to the needs and preferences of the
end-user, thereby enhancing the overall educational experience within this learning space.
3.1.2 Real-Life Quantitative Assessment
After measuring the exact dimensions and completing the 3D modeling in Revit, attention should
be paid to the acoustic properties of the room, especially given its function as a
classroom/conference room where speech intelligibility is critical. The process of measuring
reverberation time (RT) involves setting up physical measurement equipment in the actual space.
The setup consists of a signal chain, (Figure 3.0-2) in which a loudspeaker emits a sinusoidal
sweep covering the entire audible frequency range from low to high. This method ensures that
the measurement covers all frequencies typically present in speech and multimedia used in a
classroom or conference environment.
34
Figure 3.0-2 Signal Chain
Receivers are placed at various points in the room to collect reverberation time data at different
frequencies. This data is critical for analyzing the acoustic performance of the room.
Reverberation time, the time it takes for a sound to decay by 60 dB, is a key factor in
determining speech and sound intelligibility in a space. The ideal reverberation time depends on
the size of the room and its intended use. For classrooms or conference rooms, a shorter RT is
usually preferred to minimize echo and ensure clear communication. The 0.6-0.9 second interval
is the optimal time for classroom RT.
Comparing the measured RT with the ideal RT for such a space provides an objective assessment
of the acoustic quality of the room. Differences between the actual RT and the ideal RT indicate
problems that need to be addressed, such as excessive reverberation or insufficient sound
absorption. These problems can make it difficult for participants to understand spoken words or
multimedia presentations, which can seriously affect the primary function of the room.
35
After discovering any discrepancies, the next step includes analyzing the specific cause of the
acoustical problem. This may include examining the materials used in the construction of the
room, the layout of the furniture, and any acoustic treatments currently in place. Solutions can
range from simple adjustments (such as rearranging furniture or adding soft furnishings to absorb
sound) to more complex interventions (such as installing acoustic panels or redesigning aspects
of the room to improve sound diffusion).
The ultimate goal was to achieve a balance between aesthetics and functionality, ensuring that
the space would not only fulfill its purpose as a classroom or conference room but also provide a
comfortable and acoustically pleasant environment for teachers and students.
3.1.3 Digital Quantitative Assessment
Integration of the Watt Hall MBS Corner 3D model into ODEON software. This acoustic
analysis was designed to bridge the gap between theoretical predictions and the actual
reverberation times (RT) observed in space. Following the structured approach depicted in the
workflow for Odeon simulation (Figure 3.0-3), the sources and receivers need to be carefully
positioned within the software environment, reflecting their precise locations during the physical
measurement process. This step is essential to ensure the fidelity of the simulation results to the
acoustic behavior of the real space.
36
Figure 3.0-3 Workflow for ODEON Simulation (ODEON, 2023)
https://odeon.dk/product/what-is-odeon/
After accurately replicating the setup, the next stage involves assigning material properties to
individual surfaces within the model. Factors such as absorption coefficients, reflectivity, and
diffusion properties must be considered and entered in this step to reflect the true acoustic
response of these materials. The acoustic properties of most of the base materials as well as
37
being reprogrammed in Odeon can be selected for use directly. For special materials, it is
possible to customize the series parameters in the material library to achieve the desired effect.
3.2 Design Solutions and Alternatives
To advance the design of architectural acoustic elements in a given classroom or conference
room, the focus is on the integration of aesthetics and function. The design process will prioritize
not only the acoustic performance but also the visual harmony of the element with the existing
interior architecture. This ensures that they harmonize with the room while achieving the desired
acoustic attenuation.
The proposed solutions will explore a variety of shapes, including but not limited to, baffles,
clouds, and modular panels, each with unique geometric configurations such as curvilinear
forms, faceted surfaces, and perforated patterns. These designs will be evaluated for their
potential to scatter and absorb sound waves effectively, thereby reducing the RT and improving
STI within the space.
Material selection will play a key role in the performance of the design. The effects of material
density, porosity, and surface treatment on sound absorption and diffusion will be analyzed to
select appropriate material applications.
The heights and locations of acoustic elements within the space will be determined from the
results of simulations of the acoustic design. This includes considering the interaction of sound
waves with elements at different heights and angles to maximize coverage and effectiveness
across the spectrum.
38
Each design unit will be tested in ODEON software and customized simulations will be
performed to reflect the specific material properties and geometry of the proposed solution.
These simulations will provide data on how each design affects RTs across a range of
frequencies, enabling a data-driven selection process.
After selecting the optimal design based on the simulation results, detailed architectural drawings
and technical specifications will be developed. These documents will include exploded and
assembly drawings that illustrate the construction and installation process to ensure clarity and
ease of implementation.
3.3 Installation and Implementation
The Installation and Implementation phase is the transition from the theoretical design to the
proposed physical improvements in the MBS Corner on the third floor of Watt Hall. This phase
was planned and executed to ensure the highest standards of quality and efficiency while
minimizing the impact on the day-to-day operations of the building. The following detailed steps
are outlined for the process to run smoothly:
1. Procurement of Materials and Equipment
Consolidate a comprehensive list of all required materials and equipment based on final
architectural drawings and specifications. This list includes acoustic panels (homemade),
suspension/fixing systems, fasteners, adhesives, and any specialized tools required for
installation.
39
2. Pre-Construction Preparation
Completion of prefabricated acoustic element modules before construction on site. This
involves cutting, molding, and assembling the components of the acoustic elements to the
exact dimensions and specifications detailed in the architectural drawings.
3. On-Site Construction and Installation
Assemble and install each component in its designated location, adhering strictly to the
predefined specifications and standards. This includes careful alignment, securing
elements in place, and ensuring the stability and safety of the installation.
4. Post-Installation Review and Adjustments
After the installation is complete, conduct a thorough review of the project, including an
acoustic analysis to verify that the desired improvements in reverberation time and
overall acoustic quality have been achieved.
3.4 Testing
The final testing phase is the assessment of the acoustic conditions following assembly and is
divided into two distinct parts: physical measurement and user feedback student survey. The
physical measurement involves a replication of the initial quantitative assessment, but this
iteration is conducted with the acoustic element in place. Place the sound source and receivers at
the same location and collect reverberation time data in its new state. Compared to the baseline
data to evaluate any reduction in RT, an indicator of improved acoustic performance.
Concurrently, a student survey is administered to gauge subjective experiences within the
acoustically modified space. Students are queried regarding the impact of the acoustic elements
on their activities in the MBS corner, specifically whether the intervention has mitigated or
40
exacerbated acoustic conditions during varied activities. The synthesis of these quantitative and
qualitative results yields a comprehensive conclusion regarding the efficacy of the acoustic
element within the space. Based on this evaluation, recommendations for potential modifications
are proposed to inform future development, ensuring continuous improvement in the acoustic
environment.
3.5 Summary
A qualitative and quantitative assessment was undertaken beginning with an evaluation phase
that included direct observation of existing problems, a detailed student survey measuring
acoustic perceptions, and a refined problem statement formulation. The qualitative assessment
explored the complex state of existing room architecture, acoustics, and soundproofing. The
quantitative assessment, on the other hand, involved detailed physical measurements and
modeling of the existing space in a 3D environment using REVIT, which was subsequently
imported into ODEON for virtual acoustic analysis. Next came the design phase, where multiple
acoustic solutions were proposed, characterized by variations in shape, size, height, angle, and
material properties. Each design was modeled and analyzed in ODEON to predict its acoustic
performance. By basing the design on the architecture and reverberation time, the best solution
was selected. The installation and implementation phase included obtaining the necessary
supplies, equipment, construction plans, and actual construction of the selected acoustical
components. After installation, the testing phase began and included follow-up student surveys
and physical measurements to verify the acoustical condition of the components. The process is
designed to ensure enhanced student experience and acoustic conditions, and the final step is to
make recommendations for changes to the space based on conclusive data collected throughout
the study.
41
CHAPTER 4: SIMULATION AND DATA
4.1 MBS Corner in Case Studies
The study was conducted at the Master of Building Science program studio on the third floor of
USC Watt Hall. (Figure 4.0-1) The classroom is located in the southeast corner of the building
and the space serves as both an open classroom as well as a discussion area. Due to the nature of
the building itself, the third floor is an open studio with no partitions. This area was designated
as the main subject of the study due to the frequent acoustic problems. The building in this area
was surveyed and measured, and all materials were recorded. The focus area is rectangular, 1120
square feet in size and 20 feet in height, and the walls are painted. The furniture included iron
tables (with glass tops), chairs, whiteboards, and electronic displays. Single-pane glass was used
for the windows around this classroom. The floor is polished fair-faced concrete. The ceiling
surfaces are painted with fireproof material. (Figure 4.0-2)
Figure 4.0-1 USC Watt Hall MBS Corner Overview
42
Figure 4.0-2 USC Watt Hall MBS Corner Ceiling and Conference Table
The simulation of the study only includes the following area (Figure 4.0-3).
Figure 4.0-3 USC Watt Hall MBS Corner Floor Plan
43
4.2 Acoustic Modelling of MBS Corner
4.2.1 Geometrical Modelling and Calibration
Three-dimensional models of the MBS corner were created using SketchUp software (Figure
4.0-4) and then imported into ODEON, which is an acoustics software based on ray-tracing.
Figure 4.0-4 MBS Corner 3D Model in SketchUp
All furniture was generalized into rectangular blocks for testing purposes. (Figure 4.0-5) Also,
layer every surface according to the different materials used in the area. The absorption
coefficients of the materials used in testing RT in the existing space were taken from the
ODEON material library.
44
Figure 4.0-5 MBS Corner 3D Model Input In ODEON
Because the space is an open plan, the material is set to 60% absorbent in the computer model
for the open portion of the space where there are no walls. (Table 2) This factor takes into
account the probability of sound returning to space.
Table 2: Absorption coefficients of materials in existing classrooms
Location Material Material
No.
125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz ODEON Ref.
Ceiling Rough concrete No.100 0.020 0.030 0.030 0.030 0.040 0.070 Bobran, 1973
Floor Smooth
unpainted
concrete
No.101 0.010 0.020 0.020 0.020 0.020 0.050 Bobran, 1973
Glass
table top
Single pane of
glass
No.10001 0.010 0.020 0.020 0.020 0.020 0.020 Multiconsult,
Norway
Studio
Table
Plasterboard on
frame
No.4040 0.400 0.400 0.400 0.400 0.400 0.400 Fasold & Winkler,
1976
Wall and
Column
Painted plaster
surface
No.4002 0.020 0.020 0.020 0.020 0.020 0.020 Kristensen, 1984
Window Single pane of
glass
No.10002 0.010 0.010 0.020 0.020 0.020 0.020 Fasold & Winkler,
1976
Open
section
60% absorbent No.60 0.600 0.600 0.600 0.600 0.600 0.600 N/A
45
4.2.2 Simulation settings, sources, and receivers
The test employed a sound source in conjunction with two receivers. The omnidirectional sound source
symbolized the teacher's voice, positioned at the average height of a human head, 5.5 feet. The two
receivers, labeled 1 and 2, represented students attending the lecture, with their height set at the average
ear level of a seated individual, 3.6 feet. (Figure 4.0-6) In the coordinate system centered at point O, the
precise spatial coordinates of both the sound source and the receivers were determined. (Table 3)
Figure 4.0-6 Sound Source and Receivers
Table 3: Location of sound source and receivers
Description Point x (ft) Point y (ft) Point z (ft)
Sound Source (P1) 35 25 5.5
Receiver 1 18 17 3.6
Receiver 2 26 17 3.6
Setting the proper impulse response length is primarily based on Reverberation Time (RT) as
well as room size and absorption. The impulse response length should be long enough to capture
the entire reverberation period of the space being modeled. A simple way to estimate this is to set
the length to about 1.5 times the expected reverberation time (RT60) of the room. For example,
46
if the RT60 for this room is now estimated to be 1.2s, the impulse response length should be set
to at least 2 seconds to ensure that the entire reverb tail is captured. Larger rooms with lower
absorption coefficients will require a longer impulse response to accurately capture the decay of
the sound. Smaller rooms or rooms with higher absorption may require a shorter impulse
response.
Considering all the above factors, the impulse response length and number of late rays are both
set to 2000ms as a reasonable time range. These two variables can be changed in the room setup.
(Figure 4.0-7)
Figure 4.0-7 Impulse Response Length and Number of Late Rays
To ascertain the model's sealing efficacy, conducting a sound leakage simulation test is crucial.
By selecting the "3D Investigate Rays" option from the toolbar and executing a “Free Run” test,
one can examine whether any sound particles escape the confines of the space. A scenario in
which all sound dots remain encapsulated within the room signifies that the model is suitably
prepared for subsequent testing. (Figure 4.0-8)
47
Figure 4.0-8 Free Run Acoustic Leakage Test
4.2.3 Existing Room RT
The following three steps are required to properly prepare the file for analysis. Click the “Job
List” in the toolbar. Associate the source with receivers 1 and 2, designating them as P1R1 and
P1R2, respectively. Activate the "Grid" and "Multi" options before proceeding to execute all
tasks. (Figure 4.0-9)
48
Figure 4.0-9 Job List
In this simulation, the main data of interest is the RT of the two receivers. It can be noticed that
the T(30) values of receiver 1 and receiver 2 show the same trend and are not very different.
(Table 4)
In classroom acoustics, the frequency range most critical for speech intelligibility falls between
500 Hz and 4,000 Hz. This range encompasses the fundamental frequencies and most of the
important harmonics of human speech. Specifically, frequencies around 1,000 Hz to 2,000 Hz
49
are especially significant for understanding speech, as they contain the majority of phonetic
information that contributes to the clarity and intelligibility of spoken words. In this case, the RT
for this space is approximately 1.39s. (Figure 4.0-10)
Table 4: Existing room receivers 1 and 2 RT
Receiver Band(HZ) 63Hz 125Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000Hz
R1 T(20)_(s) 1.27 1.34 1.33 1.37 1.37 1.13 1.09 0.74
R1 T(30)_(s) 1.27 1.36 1.35 1.39 1.39 1.32 1.03 074
R2 T(20)_(s) 1.30 1.39 1.37 1.40 1.39 1.32 1.05 0.70
R2 T(30)_(s) 1.30 1.38 1.37 1.41 1.41 1.33 1.04 0.71
Figure 4.0-10Existing Room T(30) from R1&R2
The target reverberation time (RT) for a classroom, according to chapter 2’s literature review and
acoustic standards and guidelines, typically aims to support speech intelligibility and a
50
comfortable learning environment. The optimal reverberation time can vary based on the size of
the room and its intended use, but for most classrooms, an RT of about 0.6 to 0.8 seconds is
often recommended. For the MBS corner, the RT is higher than the target and needs to be
improved.
4.2.4 Existing Room STI
Based on the above model, the next step is to select "define grid" on the toolbar. The role of the
grid is to provide a comprehensive analysis of the acoustic properties of the entire space, not just
a few discrete points. By evaluating the acoustic performance of multiple points, it is possible to
understand how sound energy is distributed and how different building features or materials
affect sound propagation and intelligibility.
When defining a grid in ODEON, it is possible to specify the area of the room in which the grid
points are to be placed. This includes selecting the height at which the grid will be located, and
the spacing between grid points. The height of the grid is typically located at ear level in this
case 47 inch (1.2m) and is used for simulations related to speech intelligibility acoustics. The
spacing between grid points can be adjusted according to the size of the measurement range. Due
to the small size of the space, no changes were made to this item and the default value of 20 inch
(0.5m) was used. (Figure 4.0-11)
51
Figure 4.0-11 Define Grid
After defining the grid and running the simulation, ODEON calculates the selected acoustic
parameters for each grid point. This generates a detailed map showing how these parameters
vary throughout the room. This feature provides visualization tools to superimpose the calculated
acoustic parameters on a 3D model of the room. Finally an intuitive planar, elevation,
perspective view is generated. (Figure 4.0-12)
52
Figure 4.0-12 Existing Room STI from R1&R2
The Speech Transmission Index (STI) is a key metric used to assess speech intelligibility in a
space, with values ranging from 0 to 1. For classrooms and other educational environments
where clear communication is critical, use a specific STI range to ensure that speech is clear and
easily understood by all listeners. The recommended STI range for spaces suitable for
instructional use is 0.6 and above. Where 0.60 to 0.75 represents acceptable, moderate speech
intelligibility. This range is generally considered the minimum range for educational spaces.
Speech intelligibility is good to excellent when the STI is above 0.75. Values in this range are
ideal for classrooms to ensure that students clearly understand speech, which is essential for
effective learning and engagement.
53
In the case study, STI values for the two receivers in the Existing room were, R1 0.58 and R2
0.61. This represents that semantic clarity is not the most suitable for teaching and learning
activities and could be improved.
4.3 Acoustic Element Design
4.3.1 Acoustic Element Design Strategy
In order to reduce the RT in this space and enhance semantic clarity, the acoustic element can be
designed with reference to the following strategies.
1. Sound Absorbing Materials
Install sound-absorbing materials on walls, ceilings, and floors. Materials such as
acoustic panels, tiles, carpets, and curtains can significantly reduce reverberation by
absorbing rather than reflecting sound waves. Pay special attention to high-traffic areas
and surfaces that run parallel to the direction of sound propagation.
2. Acoustic Ceiling Tiles
Use acoustic ceiling tiles or surfaces hanging down from the ceiling with high sound
absorption properties. These tiles effectively reduce sound energy in the critical speech
frequency range (500 Hz to 4,000 Hz).
3. Wall Treatments
Apply acoustical wall treatments such as fabric cladding panels or acoustical plaster.
These treatments are both aesthetically pleasing and effective in controlling sound
reflections.
54
4. Soft Furnishings and Flexible Seating
Use sound-absorbing soft furniture, such as upholstered chairs and sofas, and use flexible
seating arrangements to help reduce noise levels and manage sound transmission in the
room.
5. Acoustic Partitions
Implement removable acoustic partitions or screens to help manage sound in larger
spaces or rooms with different acoustic needs.
Based on the 20 ft ceiling height of the MBS corner, implementing a lowered ceiling with
hanging surfaces can be a possible effective strategy. This approach, coupled with using soundabsorbing materials, substantially decreased reverberation by absorbing sound waves instead of
reflecting them.
4.3.2 Case Study #1 for Absorbing Material
4.3.2.1 Simulation settings
All settings regarding ODEON are consistent with the existing room test, except for the addition
of the add-on acoustic element material. The sound-absorbing material selected is wool-covered
plywood which is highlighted in orange. (Table 5) The settings that remain unchanged in
ODEON include the location of two receivers and a sound source, impulse response length,
number of late rays and the various materials of the original room.
55
Table 5: Absorption coefficients of materials in classrooms (including acoustic element)
Location Material Material
No.
125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz ODEON Ref.
Ceiling Rough concrete No.100 0.020 0.030 0.030 0.030 0.040 0.070 Bobran, 1973
Floor Smooth
unpainted
concrete
No.101 0.010 0.020 0.020 0.020 0.020 0.050 Bobran, 1973
Glass
table top
Single pane of
glass
No.10001 0.010 0.020 0.020 0.020 0.020 0.020 Multiconsult,
Norway
Studio
Table
Plasterboard on
frame
No.4040 0.400 0.400 0.400 0.400 0.400 0.400 Fasold & Winkler,
1976
Wall and
Column
Painted plaster
surface
No.4002 0.020 0.020 0.020 0.020 0.020 0.020 Kristensen, 1984
Window Single pane of
glass
No.10002 0.010 0.010 0.020 0.020 0.020 0.020 Fasold & Winkler,
1976
Open
section
60% absorbent No.60 0.600 0.600 0.600 0.600 0.600 0.600 N/A
Acoustic
element
Plywood sheets
with wool
No.3023 0.300 0.300 0.300 0.300 0.300 0.300 Kristensen, 1984
4.3.2.2 Design Solutions and RT
To investigate whether placing an acoustic element above the MBS corner can reduce the RT
(Reverberation Time) of that space, the following experiment was designed. All the experiments
used the same sound-absorbing material, and the acoustic element was of the same size and same
height but different shapes. The height is hanging above the floor 8 feet. The purpose is to study
the impact of different shapes of hanging devices on RT. (Table 6)
56
Table 6: The Effect of Hanging Different Shapes of Acoustic Elements in the Classroom on RT
(Absorbing Material)
Test # Description Image Band
(HZ)
250
Hz
500
Hz
1000
Hz
2000
Hz
4000
Hz
0 Recommend /
Ideal RT
N/A T(30)
_(s)
0.6-0.8 0.6-0.8 0.6-0.8 0.5-0.7 0.4-0.6
Base
Case
Existing Room
No acoustic
element in the
space
T(30)
_(s)
1.35 1.39 1.39 1.32 1.03
E1_Ab Flat panel
Sound-absorbing
material
# 3023
T(30)
_(s)
1.03 1.13 1.18 1.12 0.85
E2_Ab Forward bend
Sound-absorbing
material
# 3023
T(30)
_(s)
1.04 1.14 1.18 1.13 0.87
E3_Ab Backward bend
Sound-absorbing
material
# 3023
T(30)
_(s)
1.03 1.13 1.17 1.11 0.86
57
E4_Ab Circles
Sound-absorbing
material
# 3023
T(30)
_(s)
1.04 1.14 1.19 1.13 0.87
E5_Ab Loose fold
Sound-absorbing
material
# 3023
T(30)
_(s)
1.03 1.10 1.13 1.07 0.83
E6_Ab Arch
Sound-absorbing
material
# 3023
T(30)
_(s)
1.01 1.08 1.11 1.06 0.82
E7_Ab Tight fold
Sound-absorbing
material
# 3023
T(30)
_(s)
1.10 1.15 1.17 1.11 0.85
E8_Ab One-side slope
Sound-absorbing
material
# 3023
T(30)
_(s)
1.03 1.10 1.12 1.07 0.83
E9_Ab Flat + Slope T(30) 1.02 1.12 1.16 1.10 0.84
58
Sound-absorbing
material
# 3023
_(s)
4.3.2.3 STI
Based on the design of the 9 acoustic elements described above, simulations were run and STI
results and plan view visualizations corresponding to each shape were obtained. (Table 7)
Table 7:The Effect of Hanging Different Shapes of Acoustic Elements in the Classroom on STI
(Absorbing Material)
Base Case E1_Ab
R1
(STI)
0.58 R1
(STI)
0.73
R2
(STI)
0.61 R2
(STI)
0.77
E2_Ab E3_Ab
R1
(STI)
0.73 R1
(STI)
0.71
R2
(STI)
0.73 R2
(STI)
0.76
E4_Ab E5_Ab
59
R1
(STI)
0.72 R1
(STI)
0.73
R2
(STI)
0.76 R2
(STI)
0.76
E6_Ab E7_Ab
R1
(STI)
0.73 R1
(STI)
0.69
R2
(STI)
0.77 R2
(STI)
0.72
E8_Ab E9_Ab
R1
(STI)
0.72 R1
(STI)
0.71
R2
(STI)
0.77 R2
(STI)
0.75
60
4.3.3 Case Study #2 for Reflecting Material
4.3.3.1 Simulation settings
All settings regarding ODEON are consistent with the existing room test, except for the addition
of the add-on acoustic element material. The sound-absorbing material selected is a printed
plaster surface which is highlighted in light purple. (Table 8) The settings that remain unchanged
in ODEON include the location of two receivers and a sound source, impulse response length,
number of late rays and the various materials of the original room.
Table 8: Absorption coefficients of materials in classrooms (including acoustic element)
Location Material Material
No.
125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz ODEON Ref.
Ceiling Rough concrete No.100 0.020 0.030 0.030 0.030 0.040 0.070 Bobran, 1973
Floor Smooth
unpainted
concrete
No.101 0.010 0.020 0.020 0.020 0.020 0.050 Bobran, 1973
Glass
table top
Single pane of
glass
No.10001 0.010 0.020 0.020 0.020 0.020 0.020 Multiconsult,
Norway
Studio
Table
Plasterboard on
frame
No.4040 0.400 0.400 0.400 0.400 0.400 0.400 Fasold & Winkler,
1976
Wall and
Column
Painted plaster
surface
No.4002 0.020 0.020 0.020 0.020 0.020 0.020 Kristensen, 1984
Window Single pane of
glass
No.10002 0.010 0.010 0.020 0.020 0.020 0.020 Fasold & Winkler,
1976
Open
section
60% absorbent No.60 0.600 0.600 0.600 0.600 0.600 0.600 N/A
Acoustic
element
Printed plaster
surface
No.4002 0.200 0.200 0.200 0.200 0.200 0.200 Kristensen, 1984
61
4.3.3.2 Design Solutions and RT
To investigate whether placing an acoustic element above the MBS corner can reduce the RT
(Reverberation Time) of that space, the following experiment was designed. All the experiments
used the same sound-reflecting material, and the acoustic element was of the same size and same
height but different shapes. The height is hanging above the floor 8 feet. The purpose is to study
the impact of different shapes of hanging devices on RT. (Table 9)
Table 9: The Effect of Hanging Different Shapes of Acoustic Elements in the Classroom on RT
(Reflecting Material)
Test # Description Image Band
(HZ)
250
Hz
500
Hz
1000
Hz
2000
Hz
4000
Hz
0 Recommend /
Ideal RT
N/A T(30)
_(s)
0.6-0.8 0.6-0.8 0.6-0.8 0.5-0.7 0.4-0.6
Base
Case
Existing Room
No acoustic
element in the
space
T(30)
_(s)
1.35 1.39 1.39 1.32 1.03
E1_Re Flat panel
Sound-reflecting
material
# 4002
T(30)
_(s)
1.18 1.21 1.24 1.22 0.9
E2_Re Forward bend T(30) 1.21 1.23 1.25 1.19 0.85
62
Sound-reflecting
material
# 4002
_(s)
E3_Re Backward bend
Sound-reflecting
material
# 4002
T(30)
_(s)
1.1 1.15 1.17 1.11 0.91
E4_Re Circles
Sound-reflecting
material
# 4002
T(30)
_(s)
0.99 1.09 1.14 1,1 0.81
E5_Re Loose fold
Sound-reflecting
material
# 4002
T(30)
_(s)
1.24 1.25 1.25 1.21 0.88
E6_Re Arch
Sound-reflecting
material
# 4002
T(30)
_(s)
1.07 1.13 1.15 1.13 0.85
E7_Re Tight fold T(30) 1.09 1.16 1.13 1.01 0.83
63
Sound-reflecting
material
# 4002
_(s)
E8_Re One-side slope
Sound-reflecting
material
# 4002
T(30)
_(s)
0.96 0.98 0.99 0.97 0.78
E9_Re Flat + Slope
Sound-reflecting
material
# 4002
T(30)
_(s)
1.11 1.17 1.18 1.18 1
64
4.3.3.3 STI
Table 10: The Effect of Hanging Different Shapes of Acoustic Elements in the Classroom on STI
(Reflecting Material)
Base Case E1_Re
R1
(STI)
0.58 R1
(STI)
0.72
R2
(STI)
0.61 R2
(STI)
0.76
E2_Re E3_Re
R1
(STI)
0.72 R1
(STI)
0.70
R2
(STI)
0.72 R2
(STI)
0.75
E4_Re E5_Re
R1
(STI)
0.72 R1
(STI)
0.72
R2
(STI)
0.75 R2
(STI)
0.75
E6_Re E7_Re
65
R1
(STI)
0.73 R1
(STI)
0.68
R2
(STI)
0.76 R2
(STI)
0.71
E8_Re E9_Re
R1
(STI)
0.71 R1
(STI)
0.71
R2
(STI)
0.76 R2
(STI)
0.74
4.4 Data Analysis
4.4.1 Case Study #1
The dataset includes measurements of Reverberation Time (RT) across different frequencies
(250 Hz, 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz) for different shapes of hanging acoustic
elements, with the addition of a "Base Case" for comparison. This base case represents the RT
measurements in the space without any acoustic elements installed, providing a reference point
for evaluating the effectiveness of each shape. (Table 11)
66
Table 11: Case study #1 RT (Absorbing material)
Test # 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz
Base Case 1.35 1.39 1.39 1.32 1.03
E1_Ab 1.03 1.13 1.18 1.12 0.85
E2_Ab 1.04 1.14 1.18 1.13 0.87
E3_Ab 1.03 1.13 1.17 1.11 0.86
E4_Ab 1.04 1.14 1.19 1.13 0.87
E5_Ab 1.03 1.1 1.13 1.07 0.83
E6_Ab 1.01 1.08 1.11 1.06 0.82
E7_Ab 1.1 1.15 1.17 1.11 0.85
E8_Ab 1.03 1.1 1.12 1.07 0.83
E9_Ab 1.02 1.12 1.16 1.1 0.84
In order to analyze the effect of different shapes of suspensions on reverberation time, the
average reverberation time values for each shape will be compared to the base case. This
comparison will highlight the effect of each shape on RT and which shape is most effective in
reducing the reverberation time at the test frequency. (Figure 4.0-13) (Figure 4.0-14) (Figure 4.0-
15)
1. The "Base Case" has an average RT of 1.296s, which serves as a benchmark to assess the
effectiveness of each acoustic element shape.
2. All tested shapes (E1_Ab to E9_Ab) showed a reduction in average RT compared to the
base case, indicating that placing an acoustic element above the MBS corner does indeed
reduce the RT of the space.
3. The differences in average RT from the base case range from 0.22s to 0.28s, with E6_Ab
showing the most significant reduction in RT (0.28s) and E7_Ab showing the least
reduction (0.22s). This indicates that the shape of the acoustic element has a general but
insignificant effect on the reduction of reverberation time by using the same absorptive
material. The range of values reduced is not noticeable by the human ear in reality.
67
4. The shapes that resulted in the most significant reductions in RT, suggesting higher
effectiveness, are E6_Ab and E8_Ab, with reductions of 0.280 and 0.266.
Figure 4.0-13 RT_T(30) for Absorbing Material
Figure 4.0-14 Case Study #1 RT_T(30) 500Hz and 1000Hz
68
Figure 4.0-15Case Study #1 STI
4.4.2 Case Study #2
The analysis of the experiment data from the Base Case compared with E1_Re to E9_Re reveals
the following findings and summary regarding the impact of different shapes of hanging acoustic
elements on the Reverberation Time (RT) of a space. (Table 12) (Figure 4.0-16) (Figure 4.0-17)
(Figure 4.0-18)
Table 12: Case study #2 RT (Reflecting material)
Test # 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz
Base Case 1.35 1.39 1.39 1.32 1.03
E1_Re 1.18 1.21 1.24 1.22 0.9
E2_Re 1.21 1.23 1.25 1.19 0.85
E3_Re 1.1 1.15 1.17 1.11 0.91
E4_Re 0.99 1.09 1.14 1.1 0.81
E5_Re 1.24 1.25 1.25 1.21 0.88
E6_Re 1.07 1.13 1.15 1.13 0.85
E7_Re 1.09 1.16 1.13 1.01 0.83
E8_Re 0.96 0.98 0.99 0.97 0.78
E9_Re 1.11 1.17 1.18 1.18 1
69
1. The "Base Case" has an average RT of 1.296s.
2. E8_Re shows the most significant improvement in reducing RT, with an average
reduction of 0.360 seconds across all frequencies tested (250 Hz, 500 Hz, 1000 Hz, 2000
Hz, and 4000 Hz). This suggests that the shape of the acoustic element used in E8_Re is
the most effective among those tested.
3. E4_Re and E7_Re follow as the second and third most effective configurations, with
average RT reductions of 0.270 and 0.252 seconds, respectively. This indicates that their
shapes also contribute to a significant decrease in RT but to a lesser extent than E8_Re.
4. E5_Re shows the least improvement over the Base Case, with an average reduction of
0.130 seconds. This suggests that the shape used in E5_Re is the least effective among
the tested configurations in reducing RT.
5. In all experiments, there was a consistent trend towards shorter reverberation times
compared to the base case . This suggests that the presence of suspended acoustic
elements of sound-reflecting materials, regardless of their shape, generally contributes to
the reduction of reverberation time in the space.
70
Figure 4.0-16 RT_T(30) for Reflecting Material
Figure 4.0-17 Case Study #2 RT_T(30) 500Hz and 1000Hz
71
Figure 4.0-18 Case Study #2 STI
72
CHAPTER 5: INSTALLATION AND DATA
To better understand the real-world performance of the designed acoustic components, two of the
best performing case study in different materials will be selected to actually build them and test
them. This section introduces the equipment used for real life RT measurement. Based on the
results simulated from two different materials in the previous chapter, “Case Study #1 E9_Ab”
and “Case Study #2 E8_Re” are constructed respectively. The steps include constructing the 3D
construction model of the design solution, acquiring supplies and equipment, installation, and
real life testing and data.
5.1 Real-Life Existing Room RT Measurement
This chapter provides an understanding of the practical aspects of acoustical measurements at
MBS corner by examining and measuring the actual reverberation time (RT) of an existing
classroom. Reverberation time is an important acoustic parameter that indicates the time it takes
for sound to decay by 60 dB after the source has stopped. Understanding and optimizing
reverberation time is critical to improving speech intelligibility and the overall acoustic quality
of educational environments. The aim is to investigate the methods, challenges and solutions
encountered during the measurement process in real-life scenarios. It is also possible to compare
the gap between theoretical acoustics and practical real-life applications, providing guidance for
acousticians, educators, and students.
5.1.1 Equipment Setup and Calibration
The acoustic equipment that was used in this real-life RT test is called “NTi 600-000-401 Exel
Set - XL2 Acoustic Analyzer M4261 Mic XL2 ASD Cable XL2 Power Supply MR-PRO Cable
73
XL2 System Case”. (Figure 5.0-1) (Figure 5.0-2) The equipment and objects included in this
system case are listed in the following table. (Table 13)
Figure 5.0-1 NTi 600-000-401 Exel Set
https://www.markertek.com/product/nti-600-000-401/nti-600-000-401-exel-set-xl2-acousticanalyzer-m4261-mic-xl2-asd-cable-xl2-power-supply-mr-pro-cable-xl2-systemcase?gclid=CjwKCAiArY2fBhB9EiwAWqHK6nVbYKU5iLpYE6cdves0lVPPpb0CsWn3zbNtcOU
FVzik3FUW8amQVRoChDAQAvD_BwE
Figure 5.0-2 NTi 600-000-401 Exel Set Contents
74
Table 13: NTi 600-000-401 Exel Set Contents
Equipment Name Image Description Link
XL2 Acoustic Analyzer The NTi Audio hand-held
XL2 Analyzer is a
powerful Sound Level
Meter, a professional
Acoustic Analyzer, a
precision Audio Analyzer
and a comprehensive
Vibration Meter in one
instrument.
https://www.markertek.co
m/product/nti-xl2/ntiaudio-xl2-audio-andacoustic-analyzer
MR-PRO Minirator The MR-PRO Minirator
has more waveforms and
features, higher output
level capacity (+18 dBu)
and lower distortion (-96
dB @ +18 dBu) than any
other handheld audio
generator.
https://shop.ntiaudio.com/pd_minirator_
mr-procfm.cfm
M4260 microphone M4261 is a calibrated,
omnidirectional class 2
measurement microphone
running from 48V
Phantom power. It shows
excellent linearity over a
wide dynamic range from
27 dB SPL up to 144 dB
SPL.
https://shop.ntiaudio.com/pd-m4260-
measurementmicrophone.cfm
XL2 ASD cable The ASD Cable allows for
extended connections of
the NTi Audio
measurement
microphones. It supports
the transfer of the
electronic data sheet from
the microphone to the
XL2 Analyzer.
https://shop.ntiaudio.com/pd-asd-cable10m.cfm
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Begin by assembling the NTi XL2 Acoustic Analyzer setup. Connect the M4260 microphone to
the XL2 Acoustic Analyzer directly. (Figure 5.0-3) Ensure that the microphone is securely
fastened and positioned correctly. Connect the XL2 Power Supply to the Analyzer to ensure that
there is enough battery life for the duration of the tests.
Figure 5.0-3 Acoustic Analyzer Assemble and Install
Before commencing the measurements, calibrate the XL2 Analyzer and the microphone using
the provided calibration equipment. This step is crucial to ensure the accuracy of the
measurements. Follow the manufacturer’s instructions to complete the calibration process.
5.1.2 Classroom Preparation
The following steps are required to set up the space for testing. Select two measurement points
within the MBS corner, R1 and R2, which represent different locations where students might
normally sit. The red dot represents the sound source, which is where the professor is usually
located. (Figure 5.0-4) The height and location of the two receivers and one sound source are
exactly the same as in chapter 4.2.2. Take measurements in as quiet an environment as possible
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to minimize external noise interference. Close all windows and doors during measurements and
pick a time to avoid busy times in the building.
Figure 5.0-4 Classroom Set Up Plan
5.1.3 Measurement Procedure
For this test, a balloon was selected as the sound source for the reverberation time (RT)
measurement. It was called "impulsive sound source method" or more specifically, "balloon pop
method." A balloon pop generates a broadband noise signal covering a wide range of frequencies
relevant to human speech and hearing. This broadband spectrum is critical for accurately
assessing the acoustic properties of a room at the frequency of interest. The sharp impulse sound
produced when the balloon bursts closely mimics the characteristics of an ideal impulse noise
source, which aids accurate RT measurements. In addition, the simplicity and portability of the
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balloon makes it an excellent choice for in-situ measurements at various locations without the
need for electricity or complicated setup procedures. (Figure 5.0-5) (Figure 5.0-6)
Figure 5.0-5 Balloon Pop RT Test
Figure 5.0-6 Real-Life RT Test Setup
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At each measurement point (both R1 and R2), inflate a balloon to a consistent size and burst it,
capturing the impulse response using the XL2 Acoustic Analyzer. The following steps are the
details of setting up and operating on this device.
1. Open the system setting and schedule. Make the start time a few minutes in the future
while the receivers are set up in place. The duration time will be 1 minute which is the
minimum time setting for this equipment but it is enough for a balloon pop method test.
(Figure 5.0-7)
Figure 5.0-7 XL2 Equipment Setting Screenshot 1
2. Set the test to RT60 which shows in the up left of the screen. When the preset time is
reached, the device automatically starts the test. (Figure 5.0-8) Pop the balloon and wait
till the duration ends.
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Figure 5.0-8 XL2 Equipment Screenshot 2
3. Save the test data from earlier. And connect the device to the computer to read the data.
4. Conduct this process at each predefined measurement point within the classroom. It's
advisable to repeat the measurement multiple times at each point to ensure consistency
and accuracy, taking the average of these measurements for analysis.
5.1.4 Data Collection and Analysis
According to the above steps and measurements at R1 as well as R2 positions respectively, the
following RT data is collected. (Table 14)
Table 14: Real-Life Existing Room Receivers RT T(30)
Receiver 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz
R1 1.31 1.26 1.26 1.21 1.00
R2 1.33 1.28 1.30 1.24 1.03
Avg 1.32 1.27 1.28 1.21 1.01
To analyze the differences between real-life receivers and ODEON receivers, you can calculate
the average of all frequencies for each type of receiver and then compare those averages to see
any significant changes. This can give an idea of whether the digital analog (ODEON) closely
matches the physical test (real life) or whether there are significant differences. (Table 15)
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Table 15: Existing room real–life RT compare with ODEON RT
Receiver 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz Overall Avg
Real-life receivers (Avg) 1.32 1.27 1.28 1.21 1.01 1.218
ODEON Receivers (Avg) 1.36 1.4 1.4 1.325 1.035 1.304
1. The overall average across all frequencies is essentially the same for both Real-Life
Receivers and ODEON Receivers, indicating a close match between real-life
measurements and digital simulations.
2. However, when looking at individual frequencies, there are some differences. For
instance, Real-Life Receivers tend to have slightly lower values at 500-2000 Hz. While
the value is acceptably close at 250Hz and 4000Hz. (Figure 5.0-9)
3. These differences at specific frequencies suggest that while the overall acoustic behavior
is well-represented in the ODEON simulations, there might be minor discrepancies in
how certain frequencies are reproduced or captured, which could be due to various
factors including the precision of the simulation algorithms or the physical properties
being slightly different in a controlled digital environment versus real-life conditions.
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Figure 5.0-9 Existing Room Real–Life RT Compare with ODEON RT
5.2 Real Life Case Study #1 for Absorbing Material
In chapter 4.3.2 the test E9_Ab was selected for the development of a physical model. Transition
from theoretical concepts to practical applications by organizing and installing a full-size
acoustic model at the MBS corner. There will be an in-depth study of how to organize and install
full-scale models in real life, complete with measurements of different parameters.
5.2.1 Design Solution 3D Construction Model
After the E9_Ab case study, detailed construction drawings have been developed. Due to issues
encountered during reconstruction, an alternative approach of elevating the structure from the
ground has been chosen, instead of the original method involving suspension. (Figure 5.0-10)
While this approach deviates from the previous construction method, it had a minimal or
virtually negligible effect on the real-life RT testing outcomes. This finding underscores the
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flexibility of the construction process without compromising on the integrity and effectiveness of
the structure.
Figure 5.0-10 Case Study #1 Detailed Construction Drawings
The 3D construction diagram illustrates how the entire structure is supported and installed.
(Figure 5.0-11) This structure uses wood studs as "load-bearing pillars" to support the entire
acoustic panel.
Figure 5.0-11 Case Study #1 Schematic Diagram of Construction Steps
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5.2.2 Supplies and Equipment Acquisition
Create a materials list of all supplies needed according to the construction drawings. (Table 16)
The table including the selected products’ name, image, amount, size and the product link.
Table 16: Construction material list
Name Image Amount Size Link
Wood Stud 8 1.5” x 1.5” x 8’ https://www.homed
epot.com/p/Mendoc
ino-Forest-Products1-3-8-in-x-1-3-8-inx-8-ft-B-and-BetterS4S-RedwoodLumber903116/100038906
White Zip Cable
Ties
16 6" https://www.amazo
n.com/StrengthWhite-Nylon-BoltDropper/dp/B06X6
KGKWQ
PVC Foam Board 3 4’ W x 8’ L https://www.uline.c
om/BL_870/UlineFoam-CoreBoard?keywords=fo
am+board
R-13 Kraft Faced
Fiberglass
Insulation Roll
3 15” W x 32’ L https://www.homed
epot.com/p/JohnsManville-R-13-
Kraft-FacedFiberglassInsulation-Roll-15-
in-W-x-32-ft-LB1284/100317834
Cardboard Beam 8 5”W x 4.5’L N/A
Handmade
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5.2.3 Installation
The construction steps are listed below:
1. Six pieces of 8-foot wood lumber and two pieces of 9-foot wood lumber are required.
Additionally, a 1-foot cardboard extension needs to be attached to the top of two pieces
of the wood lumber before they installed in place. (Figure 5.0-12)
Figure 5.0-12 Connecting Cardboard Extension to Wood Stud
2. Paste sound-absorbing material evenly behind the three foam boards. (Figure 5.0-13)
Figure 5.0-13 Foam Board after Applying the Sound-Absorbing Material
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3. Make a few beams out of cardboard. (Figure 5.0-14)
Figure 5.0-14 Cardboard Beams
4. Attach the wood studs to the table legs using zip ties, ensuring that each wood stud is
fastened with two zip ties at both the top and bottom for secure attachment.
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5. Continue this process until all eight wood studs have been fully installed. (Figure 5.0-15)
(Figure 5.0-16)
Figure 5.0-15 Fasten the Wood Stud to the Table Leg Using Zip Ties
Figure 5.0-16 Installing Wood Studs Overview
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6. Install the pre-made cardboard beam in the middle of the two wooden bars to fix the
distance. (Figure 5.0-17) (Figure 5.0-18)
Figure 5.0-17 Installing the Pre-made Cardboard Beam
Figure 5.0-18 Installing the Pre-made Cardboard Beam Overview
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7. Lay the foam board which already coated with acoustic material, flat against the
structure. (Figure 5.0-19) (Figure 5.0-20) Repeat this procedure three times until all three
foam boards are installed.
Figure 5.0-19 Installing Foam Board
Figure 5.20 Installing Foam Board Overview
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8. Installation is complete and displayed. (Figure 5.0-21)
Figure 5.0-20 Final Installation View
5.2.4 Real-Life Testing and Data
In the practical testing section, replicate the test equipment configuration as detailed in section
5.1.2. Maintain the same positioning and height for the sound source and both receivers. Follow
all the procedures outlined in experiment 5.1.3 at this MBS corner, incorporating the newly
installed acoustic element. (Figure 5.0-21)
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Figure 5.0-21 During Case Study #1 Real-Life Testing
The table below displays the reverberation time (RT) test results for case study #1 in real life.
The "Real-Life Avg." represents the average values obtained from receiver 1 and receiver 2.
(Table 17) (Figure 5.0-22)
Table 17: Real-Life Case Study #1 Receivers RT T(30)
Receiver 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz
R1 1.01 0.96 0.99 0.89 0.82
R2 1.01 1.00 1.00 0.92 0.78
Real-Life (Avg) 1.01 0.98 0.995 0.905 0.8
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Figure 5.0-22 Case Study #1 Real-Life Testing Overview
The table below has been compiled by comparing the reverberation times (RT) observed in real
life with those simulated in the Odeon software. (Table 18)
Table 18: Real-Life Vs. ODEON Case Study #1 RT
Receiver 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz
Real-Life (Avg) 1.01 0.98 0.995 0.905 0.8
E9_Ab 1.02 1.12 1.16 1.1 0.84
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Creating a chart based on the data in Table 18 leads to the following insights. (Figure 5.0-23)
1. The Odeon software simulation generally overestimates the reverberation time across
most frequencies compared to the real-life model, with the difference becoming more
pronounced at mid frequencies (500 Hz to 2000 Hz).
2. At the lower (250 Hz) and higher (4000 Hz) ends of the frequency spectrum, the
differences are less significant, suggesting that the simulation can more accurately model
the acoustical behavior at these frequencies.
3. The pattern is consistent with that result in chapter 5.1.4.
Figure 5.0-23 Real-Life Vs. ODEON Case Study #1 RT
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5.3 Real-Life Case Study #2 for Reflecting Material
5.3.1 Design Solution 3D Construction Model
Since E8_Re case study stands out as the top performer in reflective acoustic material utilization,
for which a detailed construction model has been established. (Figure 5.0-24) Similar to its
predecessor, the framework of this structure is maintained through the use of eight wooden studs.
Figure 5.0-24 Case Study #2 Detailed Construction Drawings
The following diagram shows the steps of construction. (Figure 5.0-25)
Figure 5.0-25 Case Study #2 Schematic Diagram of Construction Steps
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5.3.2 Supplies and Equipment Acquisition
The materials and equipment are consistent with those detailed in Chapter 5.2.2. The only
difference is that instead of wrapping the PVC board with R-13 fiberglass insulation rolls, the
PVC foam board is used directly.
5.3.3 Installation
The installation steps are basically the same as what has been done in chapter 5.2.3. The
following steps need adjustment: (Figure 5.0-26)
- In Step 1, four 9ft wood studs need to be made.
- Skip Step 2, and use untreated PVC panels directly.
- In Step 4, when fixing the wood studs to the table legs, install the four extended wood
studs on the left side of the table, and the original length (8ft) ones on the right side of the
table.
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Figure 5.0-26 Case Study #2 Final Installation View
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5.3.4 Real-Life Testing and Data
All the real-life RT testing is exactly the same as 5.2.4. The positions and heights of the receivers
and the sound source remain unchanged. The result is shown below. (Table 19) (Figure 5.0-27)
Table 19: Real-Life Case Study #2 Receivers RT T(30)
Receiver 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz
R1 0.90 1.00 0.92 0.70 0.65
R2 0.94 1.01 0.95 0.71 0.69
Real-Life (Avg) 0.92 1.00 0.93 0.71 0.67
The comparison between reflecting material in real life and simulation. (Table 20)
Table 20: Real-Life Vs. ODEON Case Study #2 RT
Receiver 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz
Real-Life (Avg) 0.92 1.00 0.93 0.71 0.67
E8_Re 0.96 0.98 0.99 0.97 0.78
Figure 5.0-27 Case Study #2 Real-Life RT
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5.4 Summary
Chapter 5 details the transition from theoretical concepts to practical application, culminating in
the installation and testing of the acoustic treatment unit at Watt Hall MBS corner. This chapter
discusses the implementation of two different case studies, one featuring sound-absorbing
materials and the other featuring reflective materials. The process of implementing design
solutions in the field through to actual testing and data analysis is described.
In Case Study #1, the construction of a real-life model using absorbing materials was completed,
followed by a detailed analysis of reverberation time (RT) in the space. The real-life
measurements closely matched the ODEON simulation predictions, affirming the software's
reliability in acoustic modeling. Case Study #2 mirrored this approach but utilized reflecting
materials instead. In specific scenarios, the acoustic elements made from reflecting materials
demonstrated superior efficacy in decreasing reverberation time (RT) compared to those utilizing
absorbing materials.
The final RT data emphasize the effectiveness of both acoustic treatments, demonstrating a
tangible improvement in the acoustic quality of the MBS corner. Reverberation times were
significantly reduced, consistent with the optimal range outlined in the literature. This suggests
that while both absorptive and reflective treatments can be effective in mitigating reverberation
problems, the choice between them may depend on project-specific acoustical objectives and
design constraints.
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CHAPTER 6: CONCLUSION AND FUTURE WORK
Chapter 6 discusses the acoustic condition and design solutions in MBS corner and future work.
6.1 Conclusion
The focus of this study is to improve the acoustical quality of the MBS corner by determining its
current acoustical characteristics and developing strategies to reduce reverberation time.
Acoustics is very important in educational environments because it directly affects the efficiency
of teaching and students' comprehension. The goal of the study is to achieve a reverberation time
of less than 0.9 seconds, which is considered ideal for maintaining clear verbal communication
between teachers and students. This improvement may lead to a more effective learning
environment where students are better able to understand and retain the information provided.
6.2 Future Work
Initial research has concentrated on using ordinary acoustic materials such as foam board and
fiberglass to reduce reverberation and increase speech intelligibility. Experiments with various
non-traditional materials that might have comparable or better acoustic properties could be
conducted in the future to further this research. The sound absorption coefficients, sustainability,
and aesthetics of materials including engineered wood products, mycelium-based composites,
and recycled fabrics might all be investigated. These materials could be tested in the laboratory
before being applied to real-world environments to assess their practical suitability and
environmental impact.
99
Building on the fundamental work of this thesis, the next step might be to examine acoustic
panels of various shapes and arrangements. Emphasis will be placed on innovative designs such
as modular, foldable or interlocking panels that can be easily reconfigured to meet the specific
needs of different activities within the studio. These designs may be assessed using
computational simulations to anticipate their performance before actual prototypes are
constructed. Our objective is to offer versatile and effective solutions that are adaptable to a wide
range of acoustic demands while boosting the visual attractiveness of the area.
To validate the effectiveness of the proposed acoustic interventions, longitudinal studies could be
conducted to monitor changes over time. These studies would include ongoing acoustic
monitoring and user feedback to assess the impact of acoustic modifications on speech
intelligibility, privacy, and user satisfaction. To ascertain which acoustic strategy works best in a
given situation, comparative studies comparing various approaches could be undertaken.
6.2.1 Limitations of Current Work
The current work focuses on the study of the acoustic environment at the MBS corner. The research and
testing are solely concerned with improving the acoustic quality when the space is used as a
classroom/lecture area. There is a lack of analysis on how different situations and diverse groups of
people might affect it. Scenarios could include: student group discussions, workshops and seminars,
exhibitions and displays, networking events, peer review, and creative collaborations. At the same time,
in terms of material selection, the current work has only chosen one sound-absorbing material and one
reflective material for practical testing. In future tests, more sustainable materials could be explored. In
ODEON, one can try to expand the modeling area to get more accurate simulated results.
100
6.3 Summary
The focus of this study is to improve the acoustical quality of the MBS corner by determining its current
acoustical characteristics and developing strategies to reduce reverberation time(RT). By adding a drop
panel in a open classroom will bring down the RT. Both absorbing and reflecting materials can reduce
RT. In the studied cases involving different shapes, panels with a sloped design and reflective material
were found to be the most effective in lowering RT by 28.78%. The speech intelligibility index (STI)
increased from 0.58 to 0.73, an improvement of about 25.86%, from fair to good. This improvement may
lead to a more effective learning environment where students are better able to understand and retain the
information provided.
101
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Abstract (if available)
Abstract
In the realm of acoustics, the scientific exploration of sound and its transmission, sound waves, characterized by vibrational energy, possess the capacity to transmit data, elicit emotional responses, and impact human wellness. This investigation delves into the paramount issue of architectural acoustics within the educational institution's open studio environment, especially focusing on the conference area. The open studio functions as an intricate area accommodating diverse concurrent activities including academic programs, individual study, collective discussions, Zoom meetings, etc. The distinct characteristics of these activities necessitate varying acoustic environments. For instance, lecture sessions demand a tranquil ambiance. This dissertation addresses acoustical challenges observed in the Master of Building Science Corner of the 3rd floor of Watt Hall at the University of Southern California. Introducing a design and deployment strategy for an acoustic apparatus aimed at curtailing reverberation time and enhancing speech intelligibility. The objective centers around refining spatial regulation, facilitating effective communication, and augmenting the overall user experience. For acoustical assessment, the Odeon software was employed to develop a sophisticated analytical model.
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University of Southern California Dissertations and Theses
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Asset Metadata
Creator
Geng, Xiran
(author)
Core Title
Acoustic cumulus: acoustic improvements in the graduate building science studio
School
School of Architecture
Degree
Master of Building Science
Degree Program
Building Science
Degree Conferral Date
2024-05
Publication Date
05/29/2024
Defense Date
05/28/2024
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(original),
University of Southern California
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Building Science,OAI-PMH Harvest,reverberation time,room acoustic,speech intelligibility
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), Choi, Joon-Ho (
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Tags
reverberation time
room acoustic
speech intelligibility