Close
About
FAQ
Home
Collections
Login
USC Login
Register
0
Selected
Invert selection
Deselect all
Deselect all
Click here to refresh results
Click here to refresh results
USC
/
Digital Library
/
University of Southern California Dissertations and Theses
/
An Experimental Study Of Factors Influencing The Perception Of Auditory Flutter
(USC Thesis Other)
An Experimental Study Of Factors Influencing The Perception Of Auditory Flutter
PDF
Download
Share
Open document
Flip pages
Contact Us
Contact Us
Copy asset link
Request this asset
Transcript (if available)
Content
AN E X P E R I M E N T A L STUDY OF F A C T O R S
I N F L U E N C I N G THE P E R C E P T I O N
OF A U D ITO R Y F L U T T E R
A D isse rta tio n
P re se n te d to
the F acu lty of the G raduate School
The U niversity of S outhern C alifo rn ia
In P a rtia l F u lfillm en t
of the R e q u irem en ts fo r the D egree
D octor of P hilosophy
* .
(Speech)
by
Sanford E dw in G e rb e r
Ja n u ary 1962
UNIVERSITY O F SOUTHERN CALIFORNIA
GRADUATE SCHOOL
UNIVERSITY PARK
LOS ANGELES 7 . CALIFORNIA
This dissertation, written by
..........Sanfp.j:d.Edwin..Ge.r)?.er.......
under the direction of hl~&...Dissertation Com
mittee, and approved by all its members, has
been presented to and accepted by the Graduate
School, in partial fulfillment of requirements
for the degree of
D O C T O R OF P H I L O S O P H Y
Date........January.*...19.6 2
P R E F A C E
T his study was undertaken with the enco u rag em en t and
co n sid erab le a ssista n c e of A lb ert H. U rm e r, Ph. D ., then
P sychophysiologist at Rancho L os A m igos H o sp ita l's P sychological
S e rv ic e s. N e c e ssa ry fo rm a l c o n sid eratio n s and fu rth e r guidance
w ere re n d e re d by L eon ard W endland, P h .D ., D ire c to r of
P sy ch o lo g ical S e rv ice s at Rancho Los A m igos. F u rth e r g ratitu d e
is due to the attending staff a sso ciatio n of Rancho L os A m igos fo r
p e rm ittin g the w ork to be done th e re , and also to the m any staff
p erso n n el (esp ecially M r. Wyne P o rte r) who w ere so kind to the
w rite r during the duration of the investigation. The equipm ent
em ployed in th is study w as the p ro p erly of Rancho L os A m igos and
w as m ade available to them under a g ran t fro m the N ational F ounda
tion. M ost of the su b jects em ployed w ere p atien ts at Rancho Los
A m igos. _
A dditional su b jects w ere em ployed through the c o u rte sy of
M aurice S klar, Ph. D ., of the W adsw orth V e te ra n ’s A d m in istratio n
H ospital. The pilot study w as p e rfo rm ed with students fro m
W h ittie r C ollege, fo r whom the w rite r is indebted to L e s te r L.
H a rris , P h .D . The w rite r is fu rth e r g ratefu l to h is m any frie n d s
ii
and colleagues who v o lunteered as su b je cts.
The d ata reduction would have been a m assiv e ta sk but fo r
the av ailab ility of the IBM 709 co m p u ter at the System D evelopm ent
C o rp o ratio n (where the w rite r w as em ployed fo r m uch of the
du ratio n of the study). P a rtic u la r thanks a re due to L eonard
Staugus of the System D evelopm ent C o rp o ratio n , who is head of the
Com puting O perations G roup (P roduction D epartm ent), and to
R o b ert M cC orm ack, s ta tistic ia n with th at group.
The la rg e s t single acknow ledgm ent w as due to the w r ite r 's
w ife, L eila B. G e rb er, w ithout whose en co u rag em en t he would
n e v e r have begun graduate study.
T A B L E OF C O N T E N T S
Page
P R E F A C E .................................. ii
LIST OF T A B L E S .......................................................................... v
C hapter
I. STATEM ENT OF THE PROBLEM ; THEORETICAL
AND EX PERIM EN TA L B A C K G R O U N D ............... 1
The P ro b lem
C o n tem p o rary A uditory T heory
E x p erim e n tal B ackground
H. THE EX PERIM EN TA L P R O C E D U R E ....................... 26
Two M ethods of L im its
The Conduct of the T est
m . PRESENTATION AND INTERPRETATION O F DATA . 34
IV. SUMMARY, CONCLUSIONS, AND IMPLICATIONS . . 54
A P P E N D IX E S ................................................................................ 60
B IB L IO G R A PH Y ............................................................................. 64
iv
LIST OF T A B L E S
T able Page
1. Ages of S ubjects by G r o u p s ...................................................... 30
2. E x p erim e n tal D esign fo r T e st P r o c e d u r e ....................... 33
3. A lphanum eric D esignations of V a ria b le s ............................ 35
4. A nalysis of V a r ia n c e ................................................................... 36
5. Age D a t a ............................................................................................ 38
6 . V alues of_t fo r the D ifferen ces Among M e a n s ................. 39
7. V alues of_t fo r the D ifferen ces Among M eans T aken
with the M ethods S e p a ra te d .................................................. 41
8 . V alues of_t fo r Sound-Tim e R atio In tera ctin g w ith
M e th o d ........................................................................................... 43
9. V alues of _ t fo r the A scending M ethod Showing I n te r
action B etw een Age and Sound-T im e R a t i o ................ 44
10. V alues oM fo r the D escending M ethod Showing I n te r
action B etw een Age and Sound-T im e R a t i o ................ 45
11. M ean F lu tte r T h resh o ld s by Age as a F unction of
M ethod and Sound-T im e R a t i o ........................................... 46
v
C H A P T E R I
S T A T E M E N T OF THE P R O B L E M ;
T H E O R E T I C A L AND
E X P E R I M E N T A L
BACKGROUND
In 1874 M ayer found th at s e r ie s of soured b u rs ts , when
p re se n te d at a sufficiently rap id speed, would blend into a sen satio n
of continuous sound. * M a y e r's ex p erim en t was the f ir s t of what was
then called auditory "flic k er, " a te rm borrow ed fro m stu d ies on a
p a ra lle l phenom enon known as v isu al "flic k e r. " M a y e r's c la s s ic
e x p erim e n t rem a in e d b a sic a lly unchanged fo r about seventy-five
y e a rs , un til in 1948 M ille r suggested the use of w hite noise in stead
of pure tones as the flu tte r stim u lu s. ^ It is to M ille r th at we owe the
use of the c u rre n t te rm , auditory "flu tte r. "
R e se a rc h on au ditory flu tte r h as led to im p o rtan t c o n sid e ra
tions of beating tones, m odulating to n es, and o th er periodic
phenom ena. R ecently th e re h as been renew ed in te re s t in auditory
G. W ever, T heory of H earin g (New Y ork: John W iley &
Sons, 1949), p. 408.
o
G. A. M ille r, "The P e rc e p tio n of S hort B u rsts of N oise, "
Jo u rn a l of the A coustical Society of A m erica, XX (1948), 160-170.
1
flu tte r p e r se, leading to stu d ies of the rela tio n sh ip betw een duration
and intensity, of "n eu ra l efficiency, " of the te m p o ra l a sp e c ts of
audition, and of m ethodological innovations and ap p licatio n s. The
e x p erim en t d e sc rib e d in th is d isse rta tio n w as believed to be the
f ir s t n orm ative study of auditory flu tte r.
The purpose of th is study w as to acq u ire b a sic d ata on
auditory flu tte r to u n d erstan d it as a psychoacoustic phenom enon.
O ther re s e a r c h e r s approached auditory flu tte r from the view point of
neurophysiology, o r fro m th eo ry of p erception. T his study was
intended to be sp e cifica lly lim ited to the psychophysics of audition.
T H E P R O B L E M
S tatem ent of the P ro b lem
The p rim a ry purpose of th is study w as to d eterm in e
n o rm ative th re sh o ld v alu es of au d ito ry flu tte r fo r five age groups
sufficiently d iv erse to co n tro l d ifferen ces due to age. Secondly,
it was anticipated th at the study of au d ito ry flu tte r would add new
dim ensions to c o n tem p o rary psychoacoustic th e o rie s of the te m p o ra l
a sp e c ts of audition.
The data w ere analyzed in a way to d eterm in e the v ario u s
in te rre la tio n sh ip s am ong the v a ria b le s: age, e a r, m ethod, sound
intensity, and sound-tim e ra tio . S ev eral hypotheses w ere fo rm u lated
re la tiv e to the e ffe cts of the v a ria b le s:
1) The au ditory flu tte r freq u en cy th re sh o ld v a rie s w ith age.
2) The au ditory flu tte r freq u en cy th re sh o ld v a rie s with
psychophysical m ethod.
3) The auditory flu tte r frequency th re sh o ld is not a function
of the e a r to which the stim u lu s is p re se n te d .
4) The in ten sity of the stim u lu s does not sig n ifican tly affect
the au d ito ry flu tte r frequency th resh o ld .
5) The sound-tim e ra tio does affect the auditory flu tte r
freq u en cy th resh o ld .
6 ) Any com bination of v a ria b le s contained in the above
hypotheses m u st also be sig n ifican t.
D efinitions of T e rm s Used
The definitions p a rtic u la r to flu tte r as a phenom enon
(1 through 4 below) w ere taken fro m M ille r and T ay lo r. ^ H ow ever,
the definitions p e c u lia r to th is study w ere o rig in a l,
1) F lu tte r r e f e r r e d to any in te rru p te d sound which is
p e rc e iv e d as such by a lis te n e r.
^G. A. M ille r and W. G. T ay lo r, "The P e rc e p tio n of
R epeated B u rs ts of N oise, " Jo u rn a l of the A co u stical Society of
A m e ric a , XX (1948), 171-181. ~
2) B u rsts r e f e r re d to the sounds betw een in te rru p tio n s.
3) B u rst ra te (flu tter frequency) r e f e r r e d to the ra te at
which the sound w as in te rru p te d .
4) Sound- tim e ra tio r e f e r re d to the duty cycle of the sound
p re se n ta tio n s, the p e r cent of sound p e r unit tim e.
5) A scending m ethod of lim its re fe rre d to a p ro ced u re
w herein the stim u lu s was p resen te d at a slow b u rs t ra te
and in c re a se d to a fa s te r b u rs t ra te .
6 ) D escending m ethod of lim its re fe rre d to a p ro ced u re
w herein the stim u lu s was p resen te d at a ra p id b u rs t ra te
and d e c re a se d to a slow er b u rs t ra te .
7) A scending th resh o ld re fe rre d to a p ercep tio n of constant
noise rep la cin g one of in te rru p te d noise.
8 ) D escending th resh o ld re fe rre d to a p ercep tio n of
in te rru p te d noise rep lacin g one of constant noise.
Im portance of the Study
Since th is study w as believed to be the f ir s t one designed to
acq u ire n o rm ativ e d ata on auditory flu tte r th re sh o ld s of s tra tifie d
age groups, it w as expected to be of value to anyone in te re s te d in
em ploying such d ata fo r co m p ariso n w ith d ata g a th e red under o th er
e x p erim e n tal conditions. The p a ra lle l v isu a l phenom enon (visual
flic k e r) h as shown itse lf to be a valuable c lin ic a l and e x p erim e n tal
tool, ^ and au dito ry flu tte r m ay be expected to com plem ent v isu al
flic k e r and provide inform ation not available through the v isu al
m odality. M oreover, auditory flu tte r can supply d ata on the
p ercep tio n of b rie f stim u li fro m the e x p erim e n tal (ra th e r than
c lin ica l) view point.
T h e o re tic a l application of th ese d ata w as expected, as they
w ere of such a fo rm th a t they could be in te rp re te d in te rm s of
c o n tem p o rary th eo ry and re la te d e x p e rim e n ta l findings. M oreover,
the collection of th ese data m ust u ltim ately lead to a th eo ry of
auditory flu tte r as p a rt of the g e n eral th eo ry of au d ito ry tem p o rality .
C O N T E M P O R A R Y A U D IT O R Y T H E O R Y
W ever has review ed v irtu a lly e v e ry th eo ry of h earin g that has
5
e v e r been w orthy of s e rio u s attention. T his w as not the task h e re .
T his ta s k w as to se le c t those th e o rie s p e rtin en t to th is study. T h ree
^ E . Sim onson and J. B rozek, F lic k e r F u sio n F req u en cy ,
B ackground and A pplications, P ro je c t 21 32 004, R eport No. 2
(Randolph A ir F o rc e B ase, T exas: U nited S tates A ir F o rc e , A ir
U n iv ersity , School of A viation M edicine, 1953).
6
such th e o rie s w ere chosen: the volley th eo ry of W ever, the psycho
p h ysical th eo ry of sig n al d e tectab ility a s fo rm u lated by T an n er and
h is a sso c ia te s , and the trip le x th eo ry proposed by L ic k lid e r.
The V olley T heory
One of the m ost significant co n trib u tio n s to auditory th eo ry
in re c e n t y e a rs w as the developm ent of the volley p rin cip le into the
volley th eo ry of h e arin g by W ever and B ray. Sim ply stated , the
volley th eo ry say s that:
A group of fib e rs , if they w ork in ro tatio n , can resp o n d to
e v e ry single ex citatio n of a rap id s e rie s , w ithout an e x ce ssiv e
re q u ire m e n t being placed upon any one of them . ®
W ever indicated th at fo ur b a sic conditions w ere re q u ire d by the
volley p rin cip le : the phasic c h a ra c te r of ex citatio n , the m u ltip licity
of n erv e fib e rs , the d ifferen c e s am ong n erve fib e rs , and the
re g u la rity of the rhythm .
R elative to the phasic c h a ra c te r of ex citatio n , W ever pointed
out th a t in e v e ry cycle th e re is only one ex citatio n and it o c c u rs a t a
re g u la r phase position. R elative to the second condition, the
m u ltip lic ity of n erv e fib e rs h as been am ply d em o n strated , and
e stim a te d to be in the neighborhood of 25, 000 to 30, 000. W ever also
b eliev ed that the n erv e fib e rs have d ifferen t p ro p e rtie s which cause
6 Ib id ., p. 166.
7
them to resp o n d d ifferen tly to v a rio u s e x citatio n s, and th is can
cause them to fire in a volley r a th e r than s e ria lly o r sim ultaneously.
W ever believed the fo u rth condition, re g u la rity of rhythm , to be le s s
e sse n tia l than the o th e rs. W hile th e re is re g u la rity of n e u ra l d is
ch arg e, v a ria tio n s of rhythm do o c cu r. M oreover,
T hese flu ctu atio n s ought to becom e m ark ed under c e rta in
conditions, as when the fib e r is being stim u lated . . . at a
ra te approaching its m axim um c a p a b ilities. 7
W ever believed th a t his th eo ry was b a sic a lly a reso n an ce
th eo ry which em ployed the volley p rin cip le . He accepted the concept
of place and d e scrib e d the use of place by the volley p rin cip le.
Although the volley th eo ry b ecom es in accu rate fo r high freq u e n cie s,
volley action is tru e for the low er and in term ed iate freq u e n cie s.
W ever suggested th at a m ore lim ited place th eo ry holds fo r the
high tones.
The P sychophysical T heory of Signal D etectab ility
Signal detection th eo ry in psychophysics re p re s e n ts a m ore
g en eral case than m ost au ditory th e o rie s since it is not lim ited to
audition (in fact, its e a r lie s t fo rm u latio n s dealt with vision). A
product of the E le c tro n ic D efense G roup at the U n iv ersity of
M ichigan, the th eo ry w as d eriv ed from s ta tis tic a l decision theory.
7 Ib id ., p. 171.
The th eo ry r e s ts on th re e b a sic assu m p tio n s:
1) A se n so ry sy stem functions as a com m unication channel.
2 ) As such, se n so ry sy ste m s a re noisy channels.
3) "C e n tra l m ec h an ism s, w here d ecisio n s a re m ade, a re
capable of approxim ating optim um use of the inform ation
8
g a th e red by the p e rip h e ra l se n so ry m ec h an ism s. "
T his th eo ry a ssu m e s that the sig n al is known to the lis te n e r,
and h is p erfo rm an ce can be calcu lated fro m a knowledge of c e rta in
d e ta ils of the sig n al. M oreover, the lis te n e r is assu m ed to have
inform ation about the value of h is decision: a payoff m a trix . T here
is a m inim um num ber of p o ssib ilitie s:
1) P„(S): the p ro b ab ility of saying that the sig n al w as
0
p re s e n t when it w as, in fact, p re se n t.
2) P 0 (S): the p ro b ab ility of saying that the sig n al w as
p re s e n t when it w as, in fact, ab sen t.
3) P -(S ): the p ro b ab ility of saying th at the sig n al w as absent
s
when it w as, in fact, p re se n t.
4) Pg(S): the p ro b ab ility of saying that the sig n al w as absent
when it w as, in fact, absent.
Q
W. P . T an n er, J r . , A T heory of R eco g n itio n , T echnical
R ep o rt No. 50, E le c tro n ic D efense G roup, D ep artm en t of E le c tric a l
E n g in eerin g , U n iv ersity of M ichigan (Ann A rb o r: U n iv ersity of
M ichigan, May, 1955), p. 1.
9
The situ atio n in which such calculation is p o ssib le is called
by the th eo ry the "fixed o b serv atio n in te rv a l p ro b lem . 1,9 The
lis te n e r is to decide if he h e a rd a sig n al in noise o r if he h e a rd
noise alone. T h ere a re , th e re fo re , only two p o ssib le re sp o n se s,
each with a given probability: PgjjOO if be h e a rd signal plus noise
and PN (x) if he h eard noise alone. The p ro b ab ility of e ith e r one
o c c u rrin g is re p re se n te d by the ra tio betw een them , and re s u lts in
one of the fo u r p o ssib ilitie s liste d above. T his ra tio can be
d e te rm in e d fro m knowledge of the sig n al which gave r is e to
o b serv atio n (x). By specifying the signal en erg y (E) and the noise
pow er p e r unit bandw idth (N0), it is possible to determ ine the
p erfo rm an ce of a p e rfe ct d e te c to r (< ^J) by the equation
T ab les of d^ have been deriv ed and published.
Having knowledge of the ideal, o r p e rfe ct, o b se rv e r, it is
po ssib le to m e a su re the efficiency of an actu al o b se rv e r, > ? (eta).
One can d eterm in e the am ount of sig n al en erg y re q u ire d fo r an
actu al o b s e rv e r to re n d e r a given resp o n se , and com pare the energy
re q u ire d fo r an ideal o b se rv e r to give the sam e re sp o n se , and th is
9 Ib id ., p. 2 .
1 0 Ibid.J pp. 20-21.
10
ra tio can be taken as the value of > 7 . F ro m th is, the value of d'
can be d eterm in ed :
(d' ) 2 = 9 (2E /N 0 ).
T hus (d' ) 2 is th at value of 2E /N 0 re q u ire d to lead to the
r e c e iv e r 's p e rfo rm an c e if an ideal re c e iv e r w ere em ployed
in its p lace. * 2
It is tru e , how ever, that signal d e te ctab ility is, in p a rt, a
function of the signal duration and in ten sity . The value E em ployed
in the above equations re p re s e n ts the sp e c tra l d ensity of the
stim u lu s, and th is is p a rtly d e te rm in e d by the d u ration and
intensity. E m ploying te m p o ra l and intensive fa c to rs, it has been
shown that:
d* - k(E /N 0 ) (T /t) ^
W here E is the signal en erg y , t is sig n al duration, . . .
T . . . having the dim ensions of tim e, k is som e n u m e ric a l
constant, and NQ is the noise sp e ctru m level.
It should be p o ssib le, th e re fo re , to apply the law s of the
th eo ry of sig n al d e te ctab ility to the re s u lts of a flu tte r ex p erim e n t.
H ow ever, in a flu tte r ex p erim e n t the stim u lu s h as a sp e ctru m a lm o st
W. P . T an n e r, J r . and T. G. B ird sa ll, "D efinitions of
d' and>> a s P sy ch o p h y sical M e asu res, " Jo u rn a l of the A coustical
S ociety of A m e ric a, XXX (1958), p. 925.
1 2 Ibid.
*2 D. M. G reen , T. G. B ird sa ll, and W. P . T anner, J r . ,
"Signal D etection as a F unction of Signal In ten sity and D uration, "
Jo u rn a l of the A co u stical Society of A m e ric a , XXX (1957), p. 528.
11
equivalent to the background noise sp ecified as N0 . The value of E
in flu tte r te rm s is a lm o st (T/t)&, since the stim u lu s is o rien ted only
in tim e.
The T rip lex T heory
In 1951 L ic k lid e r proposed h is "duplex11 th eo ry of pitch
p ercep tio n , and by 1956 he had expanded it to trip le x . ^ The
trip le x th eo ry sta te s th at the e a r p e rfo rm s se v e ra l an aly ses upon
rec eiv e d sig n als, and th at these m ay be conceived of as being
sp a tia lly re la te d in th re e d im en sio n s. F requency, c ro s s -c o rre la tio n
(of the sig n als fro m the two e a rs ), and a u to c o rre la tio n a re analyzed.
T hese s e v e ra l an aly ses re q u ire m any sp e c tra l and tem p o ral data.
T his th eo ry defines the se v e ra l g en eral o p eratio n s F , G, H,
and J. System F is a num ber of com plex tr a n s fe r o p e ra to rs in the
cochlea o p eratin g along dim ension x which is re p re se n ta tiv e of
frequency. T h ere fo re , a w aveform 0 (x , f) contains only those
frequency com ponents found in the w aveform 0 (f).
O p eratio n G r e f e r s to the rec tific a tio n and lo w -p ass filte rin g
of the w aveform output fro m F. The output of o p eratio n G is a very
C. R. L ic k lid e r, "A Duplex T heory of P itch P e rce p tio n , 1 1
E x p e rie n tia , VII (1951), 128-134.
C. R. L ic k lid e r, "A uditory F req u en cy A nalysis, "
Inform ation, T heory, ed. E . C. C h e rry (New Y ork: A cadem ic
P r e s s , 1956), pp. 253-268.
12
la rg e se t of b in a ry tim e functions, one fo r each neuron, which is
re p re se n ta tiv e of a continuum along the x dim ension: I(x, t).
The next sy ste m , H , is th re e -d im e n sio n a l and re c e iv e s the
output of G . T hese dim ensions m ay be lab elled x, y, and z w herein
x is sim ply a re p re se n ta tio n of x from sy ste m F.
The y dim ension re p re s e n ts the plane in w hich co rresp o n d in g
rig h t and left x channels c ro s s . At each xy junction is a v e rtic a lly
o rien ted neuron, z. W henever sig n a ls tra v e rs in g the y dim ension
m eet at a given xy, a firin g of a neuron in the z dim ension o c cu rs.
If the e a r s have rec e iv e d the sam e sig n al, z w ill fall in the c e n te r of
the y dim ension; if the ears* sig n a ls a re out of phase, the z ^ firin g
w ill m ove tow ard the leading e a r.
The z ^ dim ension p ro je c ts on into sy stem J, re p re se n tin g the
d isc h arg e of n eu ro n s from H to J . P ro g re s s in g through H on the z ^
dim ension the sig n a ls en co u n ter a tim e delay, 5 (tau). M oreov er,
jr in c re a s e s as z ^ p ro g re s s e s upw ard th rough H tow ard J. The z _
dim ension is the a u to c o rre la to r, the y dim ension is the c r o s s -
c o rre la to r, and the jx dim ension is the frequency a n aly ze r. P a ssa g e
from H to J, then, is e sse n tia lly an a u to c o rre la tio n function; that is,
the w aveform being so p a sse d is the a u to c o rre la tio n w aveform of the
xy coincidence p assin g through the s e v e ra l tim e delays.
T h ere a re m any m ore d e ta ils of th is th eo ry which is
p a rtic u la rly a ttra c tiv e to th o se who a re co n cern ed w ith auditory
13
te m p o ra lity . In fact, it m ay account fo r som e of the gaps in the
th e o ry of signal d e tectab ility . L ic k lid e r has w ritten at som e length
with em p h asis on the physiologic c o rre la te s of these dim ensions, but
16
th is w as beyond the scope of th is study.
E X P E R I M E N T A L BACKGROUND
S tudies of A uditory F lu tte r
A t the opening of th is d isse rta tio n , re fe re n c e was m ade to
M ay er and h is o rig in a l (1874) study of auditory flic k e r. M ayer
d isc o v ere d that a s e rie s of tone b u rs ts would give r is e to a sen satio n
of continuous tone at som e c ritic a l ra te . The p a ra lle l visu al
phenom enon had alread y been dem o n strated ( e .g ., by N. F . T albot
in 1834). M ayer placed a p e rfo ra te d disc betw een a tuning fork and
its re s o n a to r, and by ro tatin g the disc c re a te d a flu tte r effect. By
th is m ethod, he w as able to determ ine flu tte r th resh o ld s as a
function of frequency. The low est th resh o ld obtained w as sixteen
b u r s ts p e r second fo r a tone of six ty -fo u r cycles p e r second, and
the h ig h est was 135 b u rs ts p e r second fo r a tone of 1024 cy cles p e r
second. As M ay er’s m ethod im proved, he w as able to e sta b lish
h ig h e r th re sh o ld s (eventually estab lish in g th resh o ld s up to 170 b u rs ts
16
J . C. R . L ic k lid e r, "T h ree A uditory T h eo ries, " P s y
chology: A Study of Science, ed. S. Kock (New York: M cG raw -H ill
Book Com pany, In c ., 1959), pp. 41-144.
14
17
p e r second).
M ayer failed to reco g n ize an a rtifa c t of h is m ethod, the
in te rru p tio n tone. K oenig (1876) and D ennert (1887) d e sc rib e d the
p resen c e of a tone equal in frequency to the ra te of in terru p tio n ;
what is now known as a m odulating tone. It w as so in te re stin g at
th at tim e that au d ito ry flic k e r becam e a technique fo r the study of
m odulating to n es. * * *
It was not until 1927 that another r e s e a r c h e r attem pted to
v e rify M a y er’s re s u lts . K u ch arsk i em ployed m ore m odern,
e le c tro n ic ap p aratu s and failed to get fusion fo r pure to n es. B ishop
a lso trie d to v erify M a y e r's w ork, but he em ployed M ay er’s m ethod
and did su c ce ssfu lly v erify the e a rly conclusions w ith the q u a lific a
tion th at com plete in te rru p tio n w as im possible with a ro tatin g d isc .
T h ere w ere a num ber of stu d ies of th is type which w ere
im p o rtan t and in te re stin g in th e ir own rig h ts , but shed little o r no
light on the su b ject of au d ito ry flu tte r as they w ere re la te d to g e n e ra l
m a tte rs of m odulation and to the su b ject of beating to n es. In fac t,
K oenig (su p ra) believ ed the in te rru p tio n tone to be a kind of com bina
tion tone as a re s u lt of a lte rn a tio n s too rap id to produce b e a ts . T his
i^W ev er, o£. c it., pp. 408-9.
1 8 Ibid.
1 9 Ibid.
was known as the beat-to n e th eo ry of h earin g in which the b a s is fo r
20
p ercep tio n w as taken to be any p erio d ic change of stim u lu s.
The f ir s t m odern study which was re la tiv e ly sp ecific to
auditory flu tte r was published by G a rn e r in 1947. H is purpose
w as not to investigate flu tte r, but to exam ine the u se fu ln e ss of
in te rru p te d to n es fo r th resh o ld testin g . He em ployed rep e titio n
r a te s from 0. 25 to 100 p e r second, and tone d u ratio n s from one to
fifty m illise c o n d s. G a rn e r pointed out that the to tal s p e c tra l en erg y
can be v aried by changing e ith e r the rep etitio n ra te o r the b u rs t
duration, but also th at only a change in duration would a lte r the
th resh o ld . T his su g g ests th at in te rru p tio n p e r se should not
influence the th resh o ld , nor should the m an n er of in te rru p tio n . The
d u ra tio n -th re sh o ld phenom enon led G a rn e r to conclude "th at the e a r
does not p e rfo rm a F o u rie r a n aly sis of these tones. " 2^
In attem pting to study these effe cts, it w as reco g n ized that
th e re are changes in the sp ectru m of the sound as the d u ration is
v aried . The use of tone b u rs ts w as d isc ard e d by M ille r in fav o r of
2 0 Ibid.
21
W. R. G a rn er, "A uditory T h resh o ld s of S hort T ones as a
F unction of R epetition R ates, " Jo u rn al of the A coustical Society of
A m e ric a , XIX (1947), 600-608. —
16
w hite noise b u rs ts to co n tro l the sp e c tra l v ariatio n . 23 The sp ectru m
of white noise is affected negligibly by changes in duration, and the
re la tiv e loudness of noise is le s s than th at of pure tones. T h ere fo re ,
noise b u rs ts m ust be m ore intense to equal the effective loudness
of pure to n es. M iller found, too, that the th resh o ld is in v ersely
re la te d to duration up to about one second, and loudness is dependent
upon d u ration up to about six ty -fiv e m illisec o n d s.
H aving co n sid ered the d u ratio n al a sp e c ts of the perceptio n
of noise b u rs ts , M ille r turned to the question of rep etitio n . 2^ With
T ay lo r, he o bserved th at the sp ectru m of rap id ly in te rru p te d noise
is s im ila r to that of continuous noise and the m odulating tone is not
in ten sified in the sp e ctru m . T h e re fo re , the m odulating tone could
not be the p e rc ep tu a l cue to the flu tte r th resh o ld , and they took
th is to be evidence a g ain st the reso n an ce th eo ry .
M ille r and T ay lo r d e scrib e d th e ir own p e rc ep tu a l e x p erien c es
upon listen in g to auditory flu tte r, and th e ir d e scrip tio n rev e ale d a
b a sic problem .
At v ery slow r a te s the noise com es on, p e rs is ts , decays to
th resh o ld , is follow ed by a p erio d of silen ce, and then com es on
again. When the ra te is in c re a se d to 10 to 15 in te rru p tio n s p e r
second, the su c ce ssiv e b u rs ts begin to fuse in a m an n er s im ila r
to the fusion obtained with sinusoidal w aves. The pitch c h a ra c te r
2 ^ M iller, op. cit.
2 ^ M iller and T ay lo r, 0 £. c it.
17
of the noise begins to em e rg e and is quite d istin c t fo r m ost
lis te n e rs at in te rru p tio n r a te s of 40 p e r second. O ver the range
from about 40 to 200 in te rru p tio n s p er second the im p re ssio n of
a definite pitch p e rs is ts , and d iffe re n tia l se n sitiv ity to ra te is
com parable in a cc u ra c y to d ifferen tial se n sitiv ity fo r the
frequency of sin u so id al w aves. F ro m about 250 to 2000
in te rru p tio n s (assum ing a sound-tim e fra c tio n of 0. 5) a qualitative
d ifference betw een the in te rru p te d noise and a steady noise can be
detected, but no pitch se em s to accom pany the changes in ra te
of in te rru p tio n . F o r m ore rap id ra te s the in te rru p te d noise is
indistinguishable from the continuous n o ise. ^
The clue is in the la s t sentence of the above quotation. Is it the
ta sk of the lis te n e r to com pare w hat he h e a rs with a continuous
n o ise ? O r is it h is task to d eterm in e, by w hatever p e rc ep tu a l
m ean s, when he h e a rs a noise which se em s to him to be continuous?
D eterm in atio n of how these questions a re to be an sw ered p rec ed e s
d ecisio n s about the m ethod to be used. If the f ir s t question is
answ ered positively, then one m ust em ploy a m ethod of p aired
co m p ariso n , and seek that flu tte r ra te at which an au d ito r d e c la re s
two physically d is s im ila r acoustic events to be identical. If one
chooses the a lte rn a tiv e , how ever, he should em ploy the m ethod of
lim its and seek a p ercep tu al d ecisio n on the p a rt of an au d ito r as to
when a sound is continuous. T h ere a re good re a so n s fo r both
ap p ro ach es, dependent upon the inform ation needed and the questions
asked.
In another study, s till a th ird question w as asked: Is th e re
2 Ib id ., p. 181.
18
a psychological scale of flu tte r s im ila r to those of pitch and
loudness?^® P o llack attem pted to c o n stru c t such a sc a le , em ploying
a unit which he called a "flut. " He found th at "the psychological
scale of flu tte r that is b ased upon n u m e ric a l e s tim a te s of F F s does
not ag ree with the scale based upon m ore conventional scalin g
n n
p ro c e d u re s. He also sought th re sh o ld s of detectio n of changes
in the b u rs t ra te , and concluded th at the d iffe re n tia l change
in c re a s e s with flu tte r ra te and is m inim um around ten in te rru p tio n s
p e r second. P o llack concluded th at "the underlying n e u ra l m ech an
ism is c o n sid ered to be m ore like th at of loudness (additive) than
like that of pitch (su b stitu tiv e). T his conclusion w as dem anded
by the in c re a se with b u rs t ra te of d etectio n of change. T hat is,
the h ig h er the b u rs t ra te , the m ore difficult w as the detectio n of
changes in th at ra te . It would seem to follow, then, th at the sam e
m echanism accounts fo r the p ercep tio n of constant noise at high
b u rs t ra te s . P o lla c k ’s conclusions su g g est the p o ssib ility th at
the cue to the flu tte r th resh o ld m ay be the ab ility (o r inability) to
d etect changes in the signal.
P o llack , "A uditory F lu tte r, " A m erican Jo u rn a l of
P sychology, LXV (1952), 544-554.
^ I b id ., p. 554.
19
In 1955 a s e r ie s of stu d ies w ere p erfo rm ed at the U n iv ersity
of Chicago w ith a purpose s im ila r to th at of the p re se n t study.
Sym m es, C hapm an, and H alstead, em ploying the m ethod of p aired
2 Q
co m p ariso n , sought th re sh o ld s fo r n o rm al individuals. W ith a
sound-tim e ra tio of 90 p e r cent and a sound intensity of 70 decibels,
they found a m ean auditory flu tte r th resh o ld of 82. 1 b u rs ts p er
second (ascending) with a stan d ard deviation of 19. 4. They con
cluded that flu tte r th resh o ld s m ay be p red ic te d to be betw een
45 and 120 b u rs ts p e r second fo r at le a st 95 p e r cent of n o rm al
individuals.
In another study they tu rn ed th e ir attention to patien ts with
on
c o rtic a l lesio n s. They em ployed the sam e m ethod and values as
above, and found no sig n ifican t d ifferen ces am ong c lin ica l groups.
F u rth e rm o re , they found that n e ith er high- n o r low -tone h earin g
lo ss could produce a low ered flu tte r th resh o ld u n less found in
conjunction with c o rtic a l dam age. C hapm an, Sym m es, and H alstead
concluded, as did P ollack, that the flu tte r th resh o ld is akin to the
29
D. Sym m es, L . Chapm an, and W. H alstead, "The F usion
of In te rm itte n t W hite N oise, " Jo u rn al of the A coustical Society of
A m e ric a , XXVII (1955), 741-748.
3°L . Chapm an, D. Sym m es, and W. H alstead, "A uditory
F lu tte r F usion in P a tie n ts with C o rtic a l A blations, " Jo u rn al of
C om parative and P h y sio lo g ical P sychology, XLVIII (1955),
421-425.
20
m echanism fo r loudness; they "assu m ed that the cue fo r the p e r
ception of flu tte r is a ju st d etectable change in loudness of the
n o is e ." 31
It se e m s to have been g e n erally concluded that auditory
flu tte r p ercep tio n is p rim a rily a c e n tra l, r a th e r than p e rip h e ra l,
function. T his has been shown conclusively in the case of visual
flic k e r, and has been d eterm in ed fo r auditory flu tte r by the C hicago
group, by P ollack, and by o th e rs. If th is is so, au ditory flu tte r
m ay be used as a m ea su re of the e ffe ctiv en e ss of c e re b ra l function,
as w ell as an in d icato r of the c e n tra l sta te of the o rg an ism .
L aw rence defined c e n tra l effe ctiv en e ss as a c e n tra l cap acity fo r
productive output (a kind of in v erse fatigue). 32 She p e rfo rm ed th ree
re la te d stu d ies te stin g the use of auditory flu tte r a s a m ea su re of
the c e n tra l sta te . She te s te d one group of su b jects se v e ra l tim e s
daily during a w ork week, a second group o v er a p erio d of s e v e ra l
w eeks during which th ere was a varying w ork load, and a th ird
group to whom she had a d m in iste re d both stim u latin g and d e p re ssin g
d ru g s. H e r re s u lts suggested th at te m p o ra ry flu tte r th re sh o ld shift
3 l Ib id ., p. 424.
32L. C. L aw rence, "A uditory F lu tte r F u sio n as a M easure of
C e n tra l E ffe ctiv en e ss, " unpublished D o cto ral d isse rta tio n , C o rn ell
U n iv ersity , 1956 (not seen), D isse rta tio n A b stra c ts, XVI (1956),
1724-1725, No. 18277.
21
was a function of w ork loadj the flu tte r th re sh o ld w as d e p re sse d at
the end of a w ork day, and w as m ore d e p re sse d in a week when the
w ork load w as heavy than in one in w hich it w as lig h te r.
D ep ressan t d rugs w ere found to d e p re ss the flu tte r th re sh o ld and
stim u la n ts w ere found to elev ate that th re sh o ld . F ro m these
stu d ies, L aw rence concluded that the auditory flu tte r th resh o ld
(ascending) does m e a su re c e n tra l e ffe ctiv en e ss. T his conclusion
a g re e s w ith th at of C hapm an, Sym m es, and H alstead, who found
d ifferen ces betw een n o rm al individuals and b ra in dam aged
individuals.
In 1957 T hurlow and Bowm an review ed the relatio n sh ip
betw een th re sh o ld of h e arin g and tem p o ral c h a ra c te ris tic s of
OO
n oise. 00 V arying the sound-tim e ra tio , they found th at th resh o ld
d e c re a se s as a function of duration, su b stan tiatin g the e a r lie r
conclusions of G a rn e r. They also found the sam e effect with
in c re a sin g b u rs t ra te , em ploying a range of r a te s fro m one to one
hundred p e r second. T his su g g ests th at while th ere a re r . m .s .
changes of sound p re s s u re w ith d e c re m e n ts in duration, th e re a re
g re a te r d e c re m e n ts of loudness. In conducting a study of auditory
flu tte r, th e re fo re , th is phenom enon m ust be taken into account in
T hurlow and R. Bowm an, "T h resh o ld fo r T h erm al
N oise as a F unction of D uration and In terru p tio n R a te ,1 1 Jo u rn al of
the A coustical S ociety of A m e ric a , XXIX (1957), 281-283.
22
the co n stru ctio n o r application of the a p p a ra tu s. F a ilu re to do so
could re s u lt in an u n d esirab le a rtifa c t.
Studies of B rie f A coustic P e rio d s
The study of ra te p ercep tio n is re la tiv e ly new in psy ch o -
acoustic re s e a rc h , and has been seen to p ro ceed in s e v e ra l
d ire c tio n s. W hat is the m inim um duration of a sound w ithin which
it is s till audible? How g re a t a tem p o ral se p a ra tio n m u st th e re be
betw een two sounds fo r them to be p erceiv ed as two sounds ra th e r
than one? At what re p e titio n ra te does a s e r ie s of p u lses fuse into
constant sound? And, fro m the psychophysiological point of view,
why? T hese questions, and o th e r s im ila r q u estio n s, re p re se n te d
one of the m ajo r a re a s of in te re s t in c o n tem p o rary psychoacoustic
re s e a rc h .
If one w ere to d e c re a se the d u ratio n s of se v e ra l p resen ta tio n s
of the sam e tone, when would it give r is e to a se n sa tio n re p o rte d as
a click ? At d urations of about two o r th ree m illisec o n d s o r less,
the stim u lu s is c le a rly definable as a click . At longer du ratio n s,
about fifty m illiseco n d s, the stim u lu s is identifiable as a tone. As
the stim u lu s duration is d e crea se d , the p ercep tio n tends to be one
of a tone which is s im ila r to a click in its sudden onset, and at
s till b rie fe r d u ratio n s (less than ten m illiseco n d s) the p ercep tio n
is that of a click which has a pitch quality known as "click
23
pitch. "34 in g e n eral, click pitch r e f e r s to the p ercep tio n of a
click w hich se em s to have tone; w h ereas, click s with tonal pitch
r e f e r to p ercep tio n s of tones which seem to begin and end with
sh a rp c lick s. The c ritic a l thing which defines a click is its
suddenness; i . e . , its tra n s ie n t n a tu re . The p resen c e of click pitch
and click s with tonal pitch m ay explain why M ille r and T ay lo r
(q. v . ) e x p erien ced the p re se n c e of pitch upon liste n in g to auditory
flu tte r. They found that the m odulating tone w as not em p h asized
and th e re fo re could not provide the pitch sen satio n which they
e x p erien ced . It was p o ssib le, then, they h e a rd pitch a ris in g from
each b u rs t at slow er r a te s . At high ra te s of in terru p tio n , they did
not ex p erien ce pitch; p erh ap s the b u rs ts w ere h e ard as c lick s.
At the C e n tra l In stitu te fo r the Deaf s e v e ra l e x p e rim e n ts have
been conducted concerned w ith m inim um audible duration and
se p ara tio n . It has been d eterm in ed that the n atu re of the sounds does
not contribute to o n e 's ab ility to d istinguish betw een one o r two
stim u li. It a p p ea rs th at th is ability is e n tire ly a function of tem p o ral
se p ara tio n . It h as been concluded by H irsh that:
W hereas te m p o ra l in te rv a ls as sh o rt as a few m illisec o n d s
a re sufficient to se p a ra te two b rie f sounds so th at a lis te n e r
w ill re p o rt th at th e re a re two (in stead of only one) sounds, a
longer se p a ra tio n tim e of betw een 15 and 20 m se c, is req u ire d
34j c . R. L ic k lid e r, "B asic C o rre la te s of the A uditory
S tim ulus, Handbook of E x p erim e n tal P sychology, ed. S. S. Stevens
(New Y ork: John W iley and Sons, I n c ., 1951), p. 1023.
24
fo r the lis te n e r to re p o rt c o rre c tly which of the two sounds
p re c e d e s the o th er.
To th is phenom enon, H irsh has given the nam e "m inim um te m p o ra l
in te rv a l. " The in te rv a ls re p o rte d above have been obtained with a
v a rie ty of stim u li p re se n te d in v ario u s o rd e rs : two click s, a
click follow ed by a tone, a tone follow ed by a click, two tones.
The problem of m inim um audible d u ration has been the
su b ject of stu d ies re la tin g it to the th re sh o ld of h earin g . F o r
exam ple, G a rn e r found that d e c re m e n ts of du ratio n produce "an
equivalent sh ift in the th resh o ld ."^® T hurlow and Bowman, also,
concluded th at "th resh o ld d e c re a se s as a function of duration . . .
L ikew ise, M ille r concluded that, due to the re la tiv e loudness of
noise as co m p ared w ith to n es, "the th re sh o ld of h earin g is low ered
no
by in c re a sin g the duration of the noise . . .
It h as a lso been concluded th at the d ifferen tial change
in c re a s e s w ith ra te and the subjective m agnitude of the changes is
additive. ^9 T his conclusion of P o lla c k 's has been su b stan tiated by
3^1. J . H irsh , "A uditory P e rc e p tio n of T em p o ral O rd e r, "
Jo u rn a l of the A coustical Society of A m e ric a , XXXI (1959), p. 759.
^ G a r n e r , loc. cit.
^ T h u rlo w and Bowm an, _op. c it., p. 281.
^ M ille r, pp. c it ., p. 160.
^ P o lla c k , loc. c it.
25
C hiatovich. It h as also been found th at "au d ito ry in te rv a ls a re
judged to be su b jectiv ely longer than co m p arab le visu al in te rv a ls.
T hese stu d ie s confirm the concept th at the e a r is a n o n -lin e a r
sy stem and the o rg an ism im p oses its own id io sy n c ra c ie s upon the
re c e iv e d p h y sical w orld. They also su g g est th a t a u d ito rs p erceiv e
flu tte r stim u li as b u rs ts of g re a te r d u ration than they actu ally a re .
A. C histovich, "D isc rim in atio n of the T im e In terv a l
B etw een Two S hort A coustic P u ls e s, " Soviet P h y s ic s - - A coustics
(T ra n sla tio n of A kuticheskii Z h u rn a l), V (1960), p. 495.
^*1. B eh ar and W. Be van, "A nalysis of the P rim e P sy c h o
p h y sical Judgm ent, " P e rc e p tu a l and M otor S k ills, X (1960), p. 82
C H A P T E R II
T H E E X P E R I M E N T A L P R O C E D U R E
T his c h ap ter is divided into two sectio n s: the f ir s t d eals
w ith the m ethodological ra tio n a le , and the second with d e ta ils of
a p p aratu s, su b jects, and te stin g p ro ce d u re.
T W O M E T H O D S O F L I M I T S
In the definitions in C h ap ter I it w as shown that two v a ria
tio n s of the m ethod of lim its w ere em ployed: ascending and
d escending. The sen satio n of the p hysical w orld is sim ultaneously
continuous and dichotom ous. It is continuous because th ere are
lev e ls of sen satio n ; fo r exam ple, one sound can be recognized as
being lo u d er than another, o r one light as b rig h te r than an o th er. It
is dichotom ous, how ever, b ecau se th e re a re c e rta in lev els at which
sen satio n does not o ccu r, c e rta in stim u lu s values cannot be p e r
ceived. It is one of the ta s k s of psychophysics to d eterm in e and to
m e a su re absolute th re sh o ld s fo r various stim u li.
In th is study, the absolute th resh o ld w as defined according to
the d ire c tio n from which it w as approached. F o r the ascending
m ethod, the flu tte r th re sh o ld w as taken to be p assin g from a
p e rcep tio n of discontinuity to one of continuity; while fo r the
26
27
descending m ethod, it w as taken to be the re v e rs e of th at.
T h ree psychophysical m ethods a re useful fo r d eterm in atio n s
of absolute th re sh o ld s: the m ethod of adjustm ent, the m ethod of
constant stim u li, and the m ethod of lim its. * T his study em ployed a
m ethod of lim its w hich could lead to re s u lts different from those
obtained w ith o th er m ethods. The e s s e n tia l difficulty of the m ethod
of lim its is in the e sta b lish m e n t of a c rite rio n .
The c rite rio n problem has led o th er r e s e a r c h e rs to use the
m ethod of p a ire d co m p ariso n in which the c rite rio n w as rep eated ly
p re se n te d to the su b ject. E a r lie r it was suggested that the choice
of m ethod m ust be d eterm in ed by the question to be answ ered. In
th is study it was decided to ask su b jects to derive a "p ercep tu al
d ecisio n " about the n atu re of the stim u lu s ra th e r than to d eterm in e
when the stim u lu s seem ed identical to an e x te rn a l c rite rio n . T here
w ere a num ber of re a s o n s fo r m aking th is choice, m ost of them of
m undane p ra c tic a lity . To p e rfo rm a thorough flu tte r te s t, a g re a t
deal of tim e w as re q u ire d . T h ere w as, th e re fo re , som e danger
of fatigue in u n n e c e ssa rily prolonging the te s t period. M oreover,
lengthy te s t se ssio n s could have e a sily led to unw illingness to
p a rtic ip a te by su b jects, and th is could have e a sily led to g ro ssly
*S. S. Stevens, "M athem atics, M easurem ent, and P sy c h o
p h y sics, " Handbook of E x g erim e n tal Psjcholog^., ed. S. S. Stevens
(New Y ork: John W iley and Sons, 1951), p. 43.
28
e rro n e o u s r e s u lts . Secondly, the ap p aratu s had been obtained p rio r
to com m encem ent of th is study, and w as intended fo r continued
use in a h o sp ital diagnostic p ro g ram . The a p p aratu s did not lend
its e lf to o th e r m ethods, and the h o sp ital re s e a rc h staff p re fe rre d to
use the m ethod of lim its fo r a ll te stin g in th is p ro g ram . T hirdly,
and m ost significantly, re s u lts obtained in e a r lie r stu d ies which
used o th er m ethods seem ed to be questionable since som e of those
stu d ies re p o rte d flu tte r p ercep tio n s at b u rs t ra te s as high as
s e v e ra l hundred p e r second. In a pilot study p e rfo rm ed in p re p a ra
tion fo r th is one, no su b ject w as able to re p o rt flu tte r at b u rs t
r a te s g re a te r than about 125 p e r second. It w as b eliev ed at that
tim e th at these data m ay have a ris e n from an a rtifa c t due to m ethod.
T h e re fo re , the choice of a d ifferen t m ethod m ight provide d ifferen t
data.
It w as fu rth e r d eterm in ed that se p a ra tio n of the ascending
and descending p ro c e d u re s w as indicated. T h ere was a p o ssib ility
th a t the th re sh o ld value m ight vary dependent upon w hether it was
approached from above o r from below . By se p a ra tin g the two
ap p ro ach es it could be seen if th resh o ld w as a function of approach,
and the two ap p ro ach es could s till be com bined in the s ta tis tic a l
a n a ly sis to d eterm in e if th e re w as an o th er th re sh o ld to be found by
a com bined m ethod ( e .g ., as th at em ployed fo r the "th resh o ld of
h e a rin g "). T hat is, it w as possible to g a th e r m eans fo r a ll
29
ascending tr ia ls , fo r a ll descending tr ia ls , and fo r both com bined.
T his was to find d ifferen ces in th resh o ld due to m ethod. It was
hypothesized th at th ese d ifferen c e s would be found.
T H E C O N D U C T O F THE T E S T
In th is sectio n s e v e ra l item s a re review ed: som e d e ta ils of
the equipm ent em ployed in the study, identification of the su b jects
chosen, and the p ro ced u re used during the te stin g of su b jects.
A pparatus
The in stru m e n t em ployed fo r flu tte r testin g was the
G ra so n -S ta d le r m odel 830S1 noise au d io m eter with a m axim um
output of ninety d ecib els (re 0. 0002 m ic ro b a r) output to P erm o flu x
PD R -8 headphones. The output could be attenuated in th ree decibel
ste p s to six ty -six d ecib els, then one six -d e c ib e l step , and then
infinite attenuation. The sig n al could be supplied to e ith e r h e ad
phone o r both by use of a se le c to r sw itch. The audiom eter
provided th ree sound-tim e ra tio s: 50, 75, and 90 p er cent.
In terru p tio n ra te s could be v aried fro m 7 to 650 b u rs ts p e r second.
S pecifications m ay be seen in Appendix A.
Subjects
The su b je cts w ere 150 adult m ales divided into 5 age groups
of 30 each. The ag es of the su b jects by groups m ay be seen in
30
Table 1. Subjects w ere re s tric te d to those w ith no h isto ry of
n eu ro lo g ical o r otological d ise ase and with n o rm al h earin g . T his
allow ed a c e rta in freedom of su b ject selectio n , since n o rm al
h e arin g at age six ty -fiv e would be c o n sid ered pathological at age
tw enty. The sta n d a rd s used w ere those published by P e te rs o n and
B eran ek which w ere g ath ered from s e v e ra l so u rc e s . T hese
sta n d a rd s m ay be found in Appendix B. To allow fo r v ariatio n in
te s t conditions, equipm ent, o r aco u stic environm ent, a c e rta in
to le ran c e from the sta n d a rd s was allow ed. The to le ran c e w as
+ 15 decibels fo r 250 and 8000 cy cles p e r second and +10 d ecib els
fo r the o th er freq u e n cie s teste d . The data obtained from au d io m etric
sc ree n in g of su b jects m ay also be seen in Appendix B.
T A B L E 1
AGES OF S U B J E C T S BY G R O U P S
G roup M ean Age Range
I 23. 58 19. 58 - 26.50
II 32. 12 29. 50 - 36. 42
in 43. 34 39. 50 - 46. 50
IV 53. 30 49.75 - 56. 41
V 62. 90 59. 50 - 66.41
o
A. P e te rs o n and L . B eranek, Handbook of N oise M e a s u re
m ent (2nd e d ., C am bridge, M a ssac h u se tts: G e n era l Radio Com pany,
1956), p. 11.
31
T e st P ro c e d u re
The su b je cts w ere given a b rie f o rien tatio n and explanation
of the n atu re of the stim u lu s. They w ere told that they would h e a r a
s e r ie s of noise b u rs ts . The noise sounded as though it had been
"chopped up. " E ach p re se n ta tio n w as differen t from the one
preced in g , but the d ifferen ces w ere so sm a ll that they m ay not be
noticed. H ow ever, su b je cts w ere told that they would notice changes
fro m e a rly p re se n ta tio n s to la te r ones, and when the noise changed
in a way th a t seem ed to be "com ing to g eth er" o r in a way that
seem ed to be "not chopped any m o re " they w ere to te ll the te s te r .
Subjects w ere also told th at so m etim es te stin g would begin with a
rough noise and they w ere to te ll the te s te r when it becam e "chopped"
o r when it s ta rte d to "fall a p a rt. " T hese in stru c tio n s w ere
im m ed iately understood by a ll the su b jects, and none of them
e x p erien ced difficulty in reco g n izin g when the stim u lu s "fell a p a rt"
o r when it stopped being "chopped. " E ach su b ject w as given a
b rie f p ra c tic e p erio d in which to e sta b lis h the d e sire d p e rc ep t of
chopping.
F o r the ascending m ethod the stim u lu s was p resen te d
in itially at th irty b u rs ts p e r second and in c re a se d in step s of th re e
b u rs ts p e r second un til the su b ject re p o rte d that he no longer
ex p erien c ed flu tte r. The in cre m e n t of th ree w as chosen only
b ecau se it w as convenient fo r the a p p aratu s and s m a lle r
32
*
in crem en ts w ere probably le s s than one jnd apart. The selectio n
of thirty b u rsts per second as the starting point was based on
resu lts of the pilot study which showed that all subjects exp erien ced
flutter at th is rate. T h erefore, th ere was no rea so n to begin
testin g at a slo w er rate. F or the descending m ethod the initial
p resentation w as at 120 bu rsts per second and d e crea sed in step s
of 3 until the subject reported a sen sation of flutter. E ach subject
was given ten tr ia ls for each te st division. T h erefore, for each
com bination of sound -tim e ratio, sound intensity, and ear, each
subject receiv ed ten ascending tr ia ls and ten descending tria ls.
T his am ounted to a total of 180 tr ia ls per subject. M eans w ere
taken for each s e r ie s of ten.
The v a ria b les w ere arranged differently for each subject
within a group, but rem ained the sam e a c r o s s groups. That is,
each subject in a group was tested in a different way, but the
corresp ondin g subjects (e. g. , II-1 and III-1) w ere tested the sam e
way. T his experim en tal design is p resen ted in Table 2.
*just noticeable difference.
T A B L E 2
E X P E R I M E N T A L D E SIG N F O R T E S T P R O C E D U R E
Subject
Sound-tim e
R atio
Sound
Intensity
O rd e r of T est
(see key)
Sound
Intensity
Sound-tim e
R atio
Subject
1 50% 72-81-90 db Ab A1 A r Db D1 D r 72 db 50-75-90 % 16
2 75% 72-81-90 db D r D1 Db A r Al Ab 81 db 50-75-90 % 17
3 90% 72-81-90 db A1 Db D r Ab A r D1 90 db 50-75-90 % 18
4 75% 81-72-90 db D1 A r Ab D r Db Al 81 db 75-50-90 % 19
5 50% 81-72-90 db A r D r Al D1 Ab Db 72 db 75-50-90 % 20
6 90% 81-72-90 db Ab Al A r Db D1 D r 90 db 75-50-90 % 21
7 90% 90-72-81 db D r D1 Db A r Al Ab 72 db 90-75-50 % 22
8 50% 90-72-81 db Al Db D r Ab A r D1 81 db 90-75-50 % 23
9 75% 90-72-81 db D1 A r Ab D r Db Al 90 db 90-75-50 % 24
10 50% 90-81-72 db A r D r Al D1 Ab Db 72 db 90-50-75 % 25
11 75% 90-81-72 db Ab Al A r Db D1 D r 81 db 90-50-75 % 26
12 90% 90-81-72 db D r D1 Db A r Al Ab 90 db 90-50-75 % 27
13 50% 72-90-81 db Al Db D r Ab A r D1 72 db 50-90-75 % 28
14 75% 72-90-81 db D1 A r Ab D r Db Al 81 db 50-90-75 % 29
15 90% 72-90-81 db A r D r Al D1 Ab Db 90 db 50-90-75 % 30
Key: Ab = ascending b in au ra l; A1 * ascending left; A r = ascending right; Db * descending b in au ral;
D1 = descending left; D r * descending rig h t.
to
00
C H A P T E R III
P R E S E N T A T I O N AND I N T E R P R E T A T I O N
OF DATA
A nalysis of D ata
A to tal of 27, 000 raw s c o re s , o r 2, 700 m eans fo r the s e rie s
of 10 tr ia ls w ere obtained on su b je cts. T hese m ean s provided the
raw d ata fo r a n aly sis by an IBM 709 h ig h -sp eed d ig ital com puter.
The co m p u ter p e rfo rm ed two ta s k s in the a n a ly sis. F ir s t, m eans
w ere calcu lated fo r a ll possible com binations of v a ria b le s in
p erm u tatio n with all o th er com binations. Secondly, a five-w ay
an aly sis of variance w as done.
The f ir s t task was to code all the e n trie s in a form suited to
the com puter. T his re q u ire d giving a le tte r designation to each of
the v a ria b le s and a num ber designation to each sta te of each
v ariab le. It was then possible to identify any m ean by a fiv e-d ig it
num ber. The f ir s t digit re p re se n te d the age group, the second digit
re p re se n te d the e a r teste d , the th ird digit re p re se n te d the m ethod of
te s t, the fourth digit re p re se n te d the sound intensity, and the fifth
digit re p re se n te d the sound-tim e ra tio . F o r each v ariab le th e re is
one e x tra n u m eric designation; fo r exam ple, while th e re w ere five
age groups, th e re is also a designation "six " which re fe r re d to all
34
35
groups com bined (see T able 3). W ith th is kind of coding, it w as
po ssib le to identify any given m ean. F o r exam ple, if one w ere to
o bserve a m ean fo r d e sig n ato r 32142, it would be known to re p re s e n t
age group III, rig h t e a r, ascending m ethod, sound in te n sitie s c o m
bined, and 75 p e r cent sound-tim e ra tio . The co m p u ter calcu lated
o v er 1, 000 m eans th at re p re s e n te d p erm u tatio n s of the s c o re s .
T A B L E 3
A L P H A N U M E R I C D E S I G N A T I O N S
OF V A R I A B L E S
V ariable A lphabetic
N um eric
1 2 3 4 5 6
Age A Gp.I Gp.H Gp.III Gp.IV Gp.V
All
G ps.
E a r B L eft Right Both Com b.
M ethod C A sc. D esc. Both
Sound
Intensity
D
72
db
81
db
90
db
Comb.
Sound-tim e
R atio
E 50% 75% 90% Comb.
The equations used by the 709 fo r the a n aly sis of variance
w ere b a sed upon those developed by L indquist. The p ro g ram was
. o rig in ally w ritten by G e n era l E le c tric , and m odified by the System
D evelopm ent C o rp o ratio n fo r use on th e ir co m p u ter. It w as
36
in te re stin g to note th at the d ata p ro c e ssin g (including key punch,
com puter o p eratio n , and printout) re q u ire d le s s than th ree h o u rs.
The actu al c alcu latio n s in the co m p u ter took about ten m inutes.
R e su lts of D ata A nalysis
The co m p u ter p ro g ra m d e sc rib e d above d eterm in ed the
significance of each v a ria b le and the significance of e v ery possible
in te rac tio n . Am ong the individual v a ria b le s (m ain effects) it was
found th at age, m ethod, and sound-tim e ra tio w ere significant,
while e a r and sound in ten sity w ere not. T hese th re e effe cts w ere
sig n ifican t at the 1 p e r cent level of confidence (see Table 4).
T A B L E 4
A N A L Y S IS O F V A R IA N C E
Source of Sum s of
V ariatio n S q u ares
D eg rees of V ariance
F reed o m E stim a te
F F
. 95
F
. 99
A 25448.1064 4 6362.0266 33. 51 2. 37 3. 32
B 866.9867 2 433.4933 2.28 2. 99 4. 60
C 1479315. 1406 1 1479315.1406 779.13 3. 84 6 . 64
D 592.7822 2 296.3911 1. 56 2. 99 4. 60
E 2492.4919 2 1246.2459 6 . 56 2. 99 4 .6 0
AB 270.6015 8 33.8252 0. 17 2. 93 4. 86
AC 108909.0313 4 27227.2578 142.87 2. 37 3. 32
AD 1117.6772 8 139.7097 0. 74 2.93 4. 86
37
T A B L E 4 ( c o n t i n u e d )
Source of
V ariatio n
Sum s of
S quares
D e g ree s of
F reed o m
V arian ce
E stim a te
F F
. 95
F
. 99
AE 12648.2961 8 1581.0370 8. 33 1. 94 2. 51
BC 17. 2500 2 8.6250 0. 05 19. 50 99. 50
BD 63.9052 4 15.9763 0.08 5.63 13.46
BE 27.6859 4 6.9215 0. 04 5. 63 13.46
CD 1340.4990 2 670.2495 3. 53 2. 99 4 .6 0
CE 766.3050 2 383.1525 2.02 2. 99 4 .6 0
DE 218.8326 4 54.7081 0.29 5.63 13.46
ABC 329.0078 8 41. 1260 0.22 2. 93 4.86
ABD 428.9421 16 26.8089 0. 14 2. 01 2.75
ABE 658.2043 16 41.1378 0.22 2.01 2. 75
ACD 4972.6509 8 621.5814 3.27 1. 94 2. 51
ACE 30963.2971 8 3870.4121 20.38 1. 94 2. 51
ADE 2174.1035 16 135.8815 0. 72 2 . 01 2. 75
BCD 357.8271 4 89.4568 0.47 5. 63 13. 46
BCE 267.7360 4 66.9340 0. 35 5.63 13.46
BDE 118.1393 8 14.7674 0. 08 2. 93 4. 86
CDE 240.0580 4 60.0145 0 . 32
5.63 13. 46
ABCD 548.4173 16 34. 2761 0 . 18 2.01 2. 75
ABCE 327.4984 16 20.4687 0 . 11 2 . 01 2. 75
ABDE 390.6372 32 12.2074 0 . 06 1. 59 1.96
38
T A B L E 4 ( c o n t i n u e d )
Source of Sum s of D eg rees of V ariance F F F
V ariatio n S q u ares F reed o m E stim a te .95 .99
ACDE 1290.4261 16 80.6516 0.42 2. 01 2.75
BCDE 1. 5326 8 0.1916 0 .0 1 2. 93 4.86
ABCDE 649.8465 32 20.3077 0 .1 1 1. 59 1.96
W ithin
C eils 461373.2344 2430 189.8655
T otal 2139059.1250 2699
In co n sid eratio n of age alone, it w as found that age w as a
significant so u rce of v ariatio n , but th at th is w as due to the v ariatio n
of only one age group. In Table 5 a re d ata re la tiv e to age.
T A B L E 5
AGE DATA
D ata
Age G roup
I H in IV V
M ean flu tte r th resh o ld 73. 91 67.67 75. 33 74, 40 76.43
S tandard deviation 27. 22 21.45 31. 64 52. 01 33.65
The d ata p re se n te d in T able 5 indicated a negligible
difference in m ean flu tte r th resh o ld s from group to group. H ow ever,
the a n aly sis of variance d eterm in ed th at age w as a sig n ifican t source
39
of v ariatio n . T h e re fo re , it w as decided to apply the p ro ced u re
b ased upon_t fo r finding the p ro b ab ility that one m ean is significantly
g re a te r than an o th er. * The re s u lts of th is p ro ced u re a re p re se n te d
in Table 6.
T A B L E 6
V A L U E S O F t_ F O R THE D I F F E R E N C E S
AMONG M E A N S*
I H HI IV V
I 4.19* 0.79 0. 19 1. 35
II 4. 67* 2. 78* 5. 09*
III 0. 35 0. 55
IV 0. 76
* t g re a te r than 2. 6 indicated a sta tistic a lly sig n ifican t difference
beyond the .01 level of confidence.
It w as ap p aren t th at the sig n ifican t so u rce of v a ria tio n due to
age w as caused by one age group (II) being sig n ifican tly d ifferen t
fro m a ll the o th e rs . None of the o th er groups w as found to be
significantly d ifferen t from each o th er. F ro m th ase d ata it w as
ap p aren t th at the flu tte r th re sh o ld did not vary w ith age in any
*C. O dell, Introduction to E d u catio n al S ta tistic s (New York:
P r e n tic e -H a ll, 1948).
sy ste m a tic m an n er. If group II w ere sig n ifican tly low er than group
I, and if the v a ria tio n w ere sy ste m a tic , then each succeeding group
should have been co rresp o n d in g ly low er. They w ere not. M oreover,
since the o th er groups did not d iffer sig n ifican tly fro m one anoth er
th ere was no cause to b elieve that group II should. No ap p aren t
re a so n fo r th is could be found. The a u d io m etric sta tu s of the
su b je cts w as co n tro lled ; so th e re w as no re a so n to believe that th is
d ifference w as due to auditory acuity. A lso, since m edical
re c o rd s w ere checked, th ere w as no cause to think th at the m em b ers
of group II su ffered any sp e c ia l physiological condition which m ight
produce the o b serv ed d ifferen ce. One could only hypothesize that
the d ifference was due to som e unknown a rtifa c t in the p ro ce d u re,
the c o n tro ls, o r even in the su b je c ts th em se lv e s. O bserving the
sig nificance ra tio s fo r group II com pared to any o th er group indicated
th at the differen ce w as r e a l. T h ere w as, how ever, one additional
c o n sid eratio n . It w as hypothesized that th e re would be sig n ifican t
d ifferen c e s due to m ethod. It w as, th e re fo re , n e c e s s a ry to see if
the differen ce obtained when the two m ethods w ere co n sid ered
se p a ra te ly w as the sam e.
C om bining a ll the age groups and o b serv in g the m ethods
independently of each o th er, it w as found th at they w ere significantly
d ifferen t at the . 01 level of confidence. The m ean flu tte r th re sh o ld
fo r the ascending m ethod w as 50. 14 b u rs ts p e r second, while th at
41
th resh o ld fo r the descending m ethod w as 96. 96 b u rs ts p e r second.
Knowing that age w as sig n ifican t due to influence of only one
group, and a lso th at m ethod w as sig n ifican t when the groups w ere
com bined, it w as im p o rtan t to exam ine the in te rac tio n betw een these
two v a ria b le s. T his in te rac tio n w as sig n ifican t at the 1 p er cent
lev el of confidence. As p reviously, the_t p ro ced u re w as applied to
m eans fo r the age groups with the m ethods se p a ra te d (see T able 7).
T A B L E 7
V A L U E S O F t F O R T H E D I F F E R E N C E S
AMONG M EAN S T A K E N W ITH
THE M E T H O D S S E P A R A T E D
A scending M ethod I H HI IV V
I 3. 72* 7.73* 0. 17 4. 57*
II 10.91* 3. 91* 7. 78*
III 7. 72* 2. 09
IV 4.45*
D escending M ethod I H HI IV V
I 10.09* 6 . 29* 0. 79 5. 55*
II 13.15* 11.89* 15.11*
III 6.27* 0. 39
IV 5. 31*
* Significant at the . 01 lev el of confidence.
42
F o r the ascending m ethod only two c o m p ariso n s w ere found
to be n o n -sig n ifican t: I x IV and III x V. T hese sam e two
co m p ariso n s w ere found to have no significant d ifferen ces fo r the
descending m ethod a s w ell. The m o st c o n sisten t re s u lt a g re e s with
that found fo r the m ethods com bined: group II alw ays d iffers
sig n ifican tly fro m a ll the o th er g ro u p s. It ap p eared th at the
v a ria tio n s of o th er groups follow ed no p a ttern .
The a n aly sis of v arian ce (T able 4) d isclo sed th at the sound
tim e ra tio w as a sig n ifican t so u rce of v ariatio n . It w as, th e re fo re ,
n e c e ssa ry to d eterm in e the so u rce of that v a ria tio n by exam ination
of each of the th re e sound-tim e ra tio s : 50, 75, and 90 p e r cent. It
was found that, with ag es and m ethods com bined, th ere was no
significant difference am ong the sound-tim e ra tio s . H ow ever, when
these ra tio s w ere o b serv ed with the m ethods se p a ra te d it w as found
that 75 p e r cent w as sig n ifican tly d ifferen t from the o th er two fo r
the ascending m ethod. T hese re s u lts are tabulated in Table 8.
T hese data indicated that th e re w as a sig n ifican t rela tio n sh ip betw een
75 p e r cent sound-tim e ra tio and the ascending m ethod. T his re s u lt
was a fu rth e r indication of the se n sitiv ity of au ditory flu tte r to the
m ethod em ployed in its p resen ta tio n , and is fu rth e r evidence of
the point m ade in C h ap ter I rela tiv e to the se lec tio n of a m ethod
ap p ro p riate to the q u estio n s asked.
43
T A B L E 8
V A LU ES OF _t FO R S O U N D - T I M E RATIO
I N T E R A C T I N G WITH M E T H O D
M ethod
R atio
50% x 75% 50% x 90% 75% x 90%
A scending M ethod 3. 50* 1. 15 2. 96*
D escending M ethod 0. 56 1. 16 1. 71
M ethods Com bined 1. 37 0.23 1.63
*_t g re a te r than 2. 60 indicated a confidence level of . 01.
The influence of the above re la tio n sh ip when d istrib u te d
am ong the v ario u s age groups was also c o n sid ered . T his m ust have
been a m assiv e effect o b serv ab le only in the case of com bined age
groups, since d ifferen t re s u lts w ere found when the ages w ere
c o n sid ered se p a ra te ly . M oreover, the an aly sis of v ariance showed a
sig n ifican t so u rce of v ariatio n due to the th ird -o rd e r in te rac tio n of
age, m ethod, and sound-tim e ra tio . F o r the case of com bined age
groups, the in te rac tio n w as found only fo r the ascending m ethod and
was found to be fo r 75 p e r cent so und-tim e ra tio only. E xam ination
of th is in te rac tio n , age by age, failed to indicate the sam e re la tio n
ship fo r four age g ro u p s. F o r groups H and IV th ere w ere no
sig n ifican t d ifferen c e s am ong the sound-tim e ra tio s fo r the
ascending m ethod. F o r G roup I the d ifference w as found fo r 75 p e r
44
cent; fo r G roup III, fo r 90 p er cent; and fo r G roup V, fo r 50 p er
cent. T hese d ata a re tabulated in Table 9.
T A B L E 9
VALUES OF t FO R THE ASCENDING METHOD
SHOWING I N T E R A C T I O N B E T W E E N
AGE AND S O U N D - T I M E RATIO
Age G roups
R atios
50% x 75% 50% x 90% 75% x 90%
I 4. 46* 1. 31 6 . 00*
II 1. 08 1. 74 4. 27*
III 2.40 6. 01* 3. 33*
IV 2. 22 1. 49 0.76
V 4. 02* 5. 31* 0.86
*_t g re a te r than 2.60 indicated a p ro b ab ility of g re a te r than .01 that
the difference was significant.
Since th is in teractio n ob serv ed in specific c a se s did not
ag ree with that o bserved in the g e n e ra l case, it w as thought n e c e ssa ry
to exam ine the descending m ethod as w ell. In the g e n eral case (age
groups com bined) th ere w ere no sig n ifican t d ifferen ces am ong the
sound-tim e ra tio s fo r the descending m ethod. H ow ever, when the
a-ge groups w ere taken se p a ra te ly , som e d ifferen ces w ere found.
Again, fo r G roup II th e re w ere no d iffe re n c e s. F o r G roup I, 50
45
p e r cent w as sig n ifican tly d ifferent; fo r G roup III, 90 p e r cent; for
G roup IV, 50 p e r cent; and fo r G roup V, 50 p e r cent. T hese date
a re tabulated in T able 10.
TA B L E 10
VA LU ES OF t FO R THE D E S C E N D IN G M E T H O D
SHOWING I N T E R A C T I O N B E T W E E N
AGE AND S O U N D - T I M E RA T IO
Age G roups
R atios
50% x 75% 50% x 90% 75% x 90%
I 3.20* 3. 50* 0. 15
II 0.42 0. 37 0 . 66
HI 1.-42 6 . 43* 5. 88*
IV 7. 08* 8 . 83* 2. 17
V 2. 95* 2. 54§ 0.60
*_t g re a te r than 2. 60 indicated a p ro b ab ility of g re a te r than . 01 that
the difference was significant.
§ _t of 2. 50 indicated a p ro b ab ility of . 05 that the d ifference was
sig nificant.
When the m ethods w ere com bined but the ages w ere co n sid ered
se p a ra te ly , th e re w ere no such d ifferen ces am ong the sound-tim e
ra tio s . The sound-tim e ra tio m ust have been a significant source
of v a ria tio n b ecau se the flu tte r th resh o ld v a rie s w ith m ethod.
F u rth e rm o re , the v ario u s age groups w ere d ifferen tially sen sitiv e
46
to changes in so u n d -tim e ra tio a s a function of m ethod, i. e . , a
given age group show ed d ifferen t re s p o n se s to v ario u s sound-tim e
ra tio s u n d er one m ethod than u n d er the o th er. The th resh o ld values
thus c o n sid ere d w ere tab u lated and a re shown in Table 11.
T A B L E 11
MEAN F L U T T E R T H R E S H O L D S BY AGE
AS A F U N C T I O N OF M E T H O D
AND S O U N D - T I M E RATIO
A scending M ethod D escending M ethod
50%
75%
90% 50% 75% 90%
49.38 57. 18 47. 77 I 101.98 93. 82 93.33
55. 87 58. 84 51. 54 H 80. 10 80. 74 78.97
43. 30 44. 93 48.23 m 110.06 108.91 96. 56
53. 03 49.84 50. 97 IV 85. 50 102.00 105.10
42. 70 48. 57 50. 03 V 108.57 103.82 104.91
48. 86 51.87 49. 71 All 97.24 97.86 95. 77
The v a ria b le s of e a r and sound in tensity w ere not found to be
sig n ifican t so u rc e s of v a ria tio n . T h ere w as no re a so n to believe th at
auditory acuity w ere co n tro lled .
To fin ally g e n e ra liz e upon the re s u lts of th is study th e re are
som e sta te m e n ts w hich m a y b e m ade. A uditory flu tte r frequency
th re sh o ld s m ay be d e te rm in e d as a function of the m ethod em ployed
47
to obtain them . Two m ethods w ere found in th is study which w ere
differen t fro m each o th er in th e ir re s u lts , and w hich gave re s u lts
d ifferen t fro m those found in e a r lie r in v estig atio n s which used s till
o th er m ethods. U nexpectedly, it was found that auditory flu tte r
frequency th re sh o ld s did not vary as a function of age, but th is
re s u lt b e a rs fu rth e r investigation. It w as also found th at the
flu tte r th resh o ld w as not a function of sound intensity, suggesting
th at it is not a p e rip h e ra l function. If, how ever, flu tte r p ercep tio n
is a c e n tra l function, it should be se n sitiv e to age.
Im plications fo r a T heory of A uditory F lu tte r
R e su lts of th is ex p erim en t su g g est a ten tativ e th eo ry of
auditory flu tte r which m ight contribute to the g e n e ra l theory of
auditory te m p o ra lity . The th re e th e o rie s d isc u sse d in C hapter I
w ere the only ones containing te m p o ra l c o n sid e ra tio n s. The volley
th eo ry explained how a flu tte r th resh o ld could o ccu r at all, while
the o th er th e o rie s provided th e o re tic a l c o n stru c ts p e rtin en t to th is
point. C oncepts d eriv ed from the trip le x th eo ry and the th eo ry of
signal d e te ctab ility tended to re ify the subjective im p re ssio n s and
hypotheses which o c c u rre d during the co u rse of the study.
It w as only a m in o r extension of the trip le x th eo ry to im pute
the p e rcep tio n of flu tte r to the dom ain of the a u to c o rre la tio n a l
an aly sis as L ic k lid e r p roposed it. Any a u to c o rre la tio n of finite
48
functions is of the sim ple form
d e scrib in g w hat happens to a given w aveform in tim e. It is a
sim ple m ultiplication, the product of w hich v a rie s w ith y , the tim e
d ifferen ce. S pecifically, the a u to c o rre la tio n function is defined as
indicating the a lte ra tio n in w aveform .
A u to c o rre latio n d e sc rib e s flu tte r p ercep tio n . The stim u lu s
alw ays had the sam e freq u en cy -am p litu d e w aveform , and changed
only in its re la tiv e d u ratio n al a sp e c ts. The a p p aratu s em ployed in
the study of flu tte r w as such as to com pensate fo r the effect of
d u ration upon loudness, so that the signal p re se n te d to the e a r w as
alw ays f(x). Any given stim u lu s, f(x), o c c u rre d over a p erio d from
Tq to T n , and th is did not v ary . D uring p erio d Tn th e re w ere som e
n u m b er of se p a ra te p rese n ta tio n s of f(x) each of which extended
from (t) to (t+:r). In o th er w ords, the v ario u s p re se n ta tio n s of
f(x) w ere se p a ra te d by X. T h e re fo re , T was the c ritic a l event u n der
study. It could be conceived of as H irs h ’s m inim um tem p o ral
se p ara tio n . L ic k lid e r c o n sid ered the a u to c o rre la tio n function to be
a h ig h e r (p erh ap s c o rtic a l) function than the frequency and phase
a n aly se s. T his a n a ly sis m u st have been dichotom ous w ithin the
definitions of th is study: the stim u lu s w as o r w as not in te rru p te d .
R(jr) ■ lim f f(t)f(t+5r)dt
49
If !r was le s s than the m inim um te m p o ra l se p a ra tio n the auto-
c o rre la tio n a l a n aly sis would indicate
f(t) - f(t+!r).
T hat is, the an aly sis would re s u lt in a p ercep tio n of no pause.
T his w as re p re se n ta tiv e of the ascending m ethod, but the a p p lic a
tion in re v e rs e to the descending m ethod was obvious. T his could
be due to the fa ilu re of the volley action, as W ever suggested.
The type of an aly sis em ployed in the th eo ry of signal
d e tectab ility was able to fu rth e r augm ent the th eo ry of flu tte r.
In te rm s of those fo rm u latio n s it w as c le a r th at the n atu re of the
signal to be detected w as specifiable and was known to the su b ject.
F u rth e rm o re , the su b ject was told that the d e s ire d signal would
o ccu r, and it w as h is task to indicate when it o c c u rre d . Such a
fo rm u latio n of flu tte r was w ithin the definitions of the th eo ry of
signal d e tectab ility . The problem w as to define the id eal o b se rv e r
fo r a flu tte r signal, and th is problem led to fo rm u latio n s com bining
c o n stru c ts of the th eo ry of signal d etectab ility w ith som e from the
trip le x th eo ry as in te rp re te d above.
F o r an id eal o b se rv e r it w as n e c e ssa ry to d eterm in e d 1 as
an in d ic ato r of h is ability. W ith a flu tte r sig n al, th is d1 m u st be
b ased u p o n > . The sta te of the study of au ditory te m p o ra lity was
such that no n u m eric estim atio n could be m ade. It could only be
sta te d that d 1 m u st be a function of som e c ritic a l value of > y et to be
50
fin ally d eterm in ed :
d' » f(trc).
T h ere w ere techniques to d eterm in e the beh av io r of an
id eal o b se rv e r; th e re fo re , a review of the s ta tis tic a l th eo ry of
signal d e te ctab ility was m ade to a s s is t in fu rth e r lim itin g the
pro b lem . The p erfo rm an ce of the id eal o b se rv e r in the g e n eral
(or a b stra c t) case provided clu es.
The th eo ry of the id eal o b se rv e r dates fro m about 1950 when
it w as p re se n te d (in one case) by Law son and U hlenbeck. * T hese
a u th o rs w ere able to re la te it to som e e a r lie r w ork with p a rtic u la r
re fe re n c e to ra d a r. The b eh av io r of the ideal o b se rv e r was
d e sc rib e d a s follow s:
We do not know w hether th e re is a c u rre n t p re s e n t o r not
and . . . we have to decide th is question on the b a s is of N
o b se rv atio n s. The question then a ris e s how to m ake use of
th ese o b se rv atio n s in the b e s t possible way, so th at the co n
clu sio n we draw from th ese o b serv atio n s, nam ely, w hether
the c u rre n t is p re se n t o r not, w ill have the b e st chance to be
rig h t. We sh a ll say th at the ideal o b s e rv e r alw ays m akes use of
the o b se rv atio n s in th is way, and we sh a ll speak of the ideal
o b s e rv e r c rite rio n . 3
The e r r o r s d e sc rib e d p rev io u sly a re fre q u e n tly known a s the e r r o r
of the f ir s t kind, P„(S), and the e r r o r of the second kind, Pz(S).
O S
^ Ja m e s L . Law son and G eorge E . U hlenbeck, T h resh o ld
Signals (New Y ork: M cG raw -H ill Book Com pany, In c ., 1950).
3Ibid., pp. 167-8.
51
T his lea d s to a fo rm u latio n in th ese te rm s .
A nother c rite rio n . . . is to keep the p robability of e r r o r
of the f ir s t kind le s s than o r equal to a p re s c rib e d value and
m inim ize the p ro b ab ility of e r r o r of the second kind. A fam ous
th eo re m of N eym an and P e a rs o n sta te s that a likelihood ra tio
te s t w ill sa tisfy th is c rite rio n . ^
As pointed out by Law son and Uhlenbeck, the N ey m an -P earso n
5
th eo ry is p ra c tic a lly id en tical w ith the ideal o b se rv e r th eo ry .
E m ploying the N e y m an -P e arso n theory, it w as p o ssib le to
fu rth e r sim plify the situ atio n re la tiv e to au ditory flu tte r. If a ll
the p a ra m e te rs of the sig n al except tim e of a rriv a l a re known and
constant, then the m ultiple o b serv atio n m ay be tre a te d as one.
T hat is,
One could tr e a t the to ta l signal s-^(t) + S2 (t) . . . sm (t)
as a single sig n al . . . the o b serv atio n in te rv a l would m ere ly
be b ro k en up into a se t of disconnected p a rts . ®
T h e re fo re , the e n tire te s t s e rie s m ay be co n sid ered as but one
(disconnected) p re se n ta tio n during which a d e sire d event w ill o ccu r.
U nder the N e y m a n -P e a rso n th eo ry two hypotheses a re e sta b lish e d
which coincide w ith those of th is study: the signal is p re s e n t o r the
^W ilbur B . D avenport, J r . , and W illiam L . Root, An
Introduction to the T heory of Random Signals and N oise (New York:
M cG raw -H ill Book C om pany, In c ., 1958), p. 323.
L aw son and U hlenbeck, lo c. c it.
6C a rl W. H e lstro m , S ta tistic a l T heory of Signal D etection
(New Y ork: P e rg am o n P r e s s , 1960), p. 167.
sig n al is not p re s e n t. T hese hypotheses have c e rta in a p rio ri
p ro b a b ilitie s which m ay be applied to a likelihood ra tio , /[ (x). The
th eo ry fu rth e r sta te d th at a c e rta in value, A q , is assu m ed to sa tisfy
the d e sire d conditions fo r the two kinds of e r r o r . T his is known as
the N e y m an -P e arso n c rite rio n . If Ax w ere le s s than A q then the
o b s e rv e r would sta te th at th e re w as no sig n al; if it w ere g re a te r,
n
he would sta te th at the signal w as p re se n t. 1
F o r the te stin g conducted in th is study, the su b je cts w ere
told that the d e sire d signal would o ccu r. W ith each succeeding
p resen ta tio n , the a p r io ri p ro b ab ility of the o c c u rre n c e of the
d e sire d sig n al in c re a se d . Since the re la tiv e d u ratio n s of the sig n als
w ere a lte re d w ith each p resen ta tio n , the pow er density also changed.
Since A x re p re s e n te d a ra tio betw een the pow er density functions of
noise alone and sig n al plus noise, then A x m u st have in c re a se d with
eac h succeeding p resen ta tio n . As sta te d above, when A x exceeds
A 0 o b s e rv e r w ill sta te th at the signal w as p re s e n t. T his m eant
th at the actu al o b s e rv e r determ in ed the p ro b ab ility of a false a la rm
( e r r o r of the f ir s t kind) which changed w ith each succeeding
p re se n ta tio n until th a t p ro b ab ility w as so low he m u st re p o rt th at the
sig n al did o c c u r. E sse n tia lly , then, su b je cts re p o rte d when a signal
cea sed being in its o rig in a l sta te .
To su m m a riz e , the p ro c e s s of flu tte r p ercep tio n w as
explained w ith c e rta in m ath em a tica l fo rm u latio n s w hich w ere
o rig in a lly d eriv ed fo r application to ra d a r and la te r applied to
psychophysics. The te stin g e sta b lish e d c e rta in conditions fo r the
su b je cts which n e c e s s a rily c a r rie d w ith them c e rta in a p rio ri
p ro b a b ilitie s. The n atu re of th ese p ro b a b ilitie s w as such that the
n e c e s s a ry o b se rv atio n was that the su b je c ts p e rc eiv e d what the
stim u lu s had probably c ea sed to be, and had only one a lte rn a tiv e
av ailab le.
The application of the N e y m a n -P e a rso n c rite rio n explained
how the data acq u ired in th is study indicated low er th re sh o ld s than
those obtained by p rev io u s in v e stig a to rs. T h ere m u st have been a
com plex "n e u ro -m a th e m a tic " p ro c e ss o p e ra tin g upon these signal
d ata w ithin the lim ita tio n s se t by th is ex p erim e n t. When a given
ex p erim e n t se ts d ifferen t lim ita tio n s and d ifferen t c r ite r ia , it
n e c e s s a rily follow s that the re s u lts w ill be d ifferen t.
The fo rm u latio n of the th eo ry of flu tte r indicated an additional
re s u lt w hich w as not im m ediately d eriv ed e x p erim e n tally . In
co n sid era tio n of the a p rio ri p ro b a b ilitie s, it was se en th at su b je cts
d e te rm in e d what the stim u lu s had c e a se d to be and, th ereb y ,
d e te rm in e d the n atu re of the te s t sig n al.
C H A P T E R IV
SUMM ARY, CON CLU SION S,
AND I M P L I C A T I O N S
Sum m ary
The p rim a ry purpose of th is study w as to d eterm in e
no rm ative th resh o ld values of auditory flu tte r fo r five age groups
sufficiently d iv erse to co n tro l d ifferen ces due to age. Secondly, it
w as an ticip ated th at the study of auditory flu tte r would aid in u n d e r
standing and in te rp re tin g co n tem p o rary psychoacoustic th e o rie s of
the tem p o ral a sp e c ts of audition.
The lite ra tu re on the su b ject of flu tte r w as review ed, and it
w as found th at p rio r re s e a rc h re s u lts w ere inconclusive and con
flicting. Although M ayer d isco v ered the flu tte r phenom enon in 1874,
it w as m o re than fifty y e a rs until h is data w ere su b stan tiated . The
c o n tem p o rary flu tte r te s t and stim u lu s w ere developed by M iller in
1948. He w as the only one to re p o rt a pitch sen satio n a sso c iated
with flu tte r, but th is h as n e v er been su b stan tiated . F u rth e rm o re ,
M ille r and T ay lo r found flu tte r th re sh o ld s as high as 2, 000 b u rs ts
p e r second, and th ese high th resh o ld s have not been d isco v ered by
o th e r in v e stig a to rs. The U n iv ersity of Chicago group attem pted
flu tte r th resh o ld d e term in atio n s upon p e rso n s who had su ffered
54
55
c o rtic a l lesio n s, and found sig n ifican t d ifferen c e s betw een these
p atien ts and a co n tro l group. S im ila rly , L aw rence found th at the
flu tte r th resh o ld v a rie s with the " c e n tra l e ffe ctiv en e ss" of the
su b ject. The m ain difficulty in a ll th ese stu d ies w as the lack of a
stan d ard o r norm as sought by the p re s e n t study.
A to ta l of 150 n o rm al adult m a le s w ere te ste d fo r the
au d ito ry flu tte r frequency th resh o ld by the m ethod of lim its. The
su b je cts em ployed in the e x p erim e n t w ere divided into five age
groups which could p re s e n t psychophysiological d ifferen c e s. The
five v a ria b le s em ployed in the study w ere taken to be the fa c to rs
co ntributing to flu tte r p ercep tio n : age, e a r, psychophysical m ethod,
sound intensity, and sound-tim e ra tio . The data g ath ered in the
te s ts w ere subjected to an a n aly sis of v arian ce from which the
re s u lts w ere d eterm in ed . C o n sid eratio n of the re s u lts led to
s e v e ra l conclusions.
C onclusions
W ithin the design and lim ita tio n s of th is study, the follow ing
conclusions seem ed w arran ted :
1) The auditory flu tte r freq u en cy th re sh o ld does not vary
with age.
2) The auditory flu tte r frequency th resh o ld v a rie s with
p sychophysical m ethod.
56
3) The au ditory flu tte r freq u en cy th re sh o ld does not v ary as
a function of the e a r to which the stim u lu s is p re se n te d .
4) The auditory flu tte r freq u en cy th re sh o ld does not v ary as
a function of the sound in ten sity of the stim u lu s.
5) The auditory flu tte r freq u en cy th re sh o ld v a rie s with
sound-tim e ra tio .
W hile the above conclusions w ere b ased on the analyzed data,
c e rta in lim ita tio n s and q u alificatio n s w ere m ade ap p aren t by that
a n a ly sis. The f ir s t conclusion w as rev e ale d by the s ta tis tic a l
p ro c e d u re s em ployed, but it cannot be fully accepted. Only one of
the five age groups (II) w as significantly d ifferen t fro m the o th e rs.
R e su lts of v isu al flic k e r e x p e rim e n ts have supported the hypothesis
th at th re sh o ld v a rie s with age. T his seem ed to be a reaso n ab le
hypothesis fo r th is study. The a n aly sis of v arian ce indicated the
p resen c e of an age fa c to r, but fu rth e r an aly sis n arro w ed th is to one
group. W hile it is e n tire ly possible that au ditory flu tte r is not
se n sitiv e to age d ifferen c e s, fu rth e r d ata a re re q u ire d on th is point.
The conclusion re g a rd in g m ethod was m o st stro n g ly
sup ported by the evidence. The v arian ce due to m ethod w as fa r
g re a te r than that due to any o th e r v ariab le. T here w as little
question that the ascending m ethod used h e re in w as a d ifferen t one
than the descending m ethod. M o reo v er, th ere was a g re a te r
57
difference am ong the age groups fo r the descending m ethod than fo r
the ascending m ethod.
The conclusion re la tiv e to sound in te n sity fo rc e s the
assu m p tio n th at th is was tru e only fo r those (high) in te n sitie s
em ployed. It was possible that low er in te n sitie s could significantly
influence the au d ito ry flu tte r frequency th resh o ld . T his sam e
qualification holds fo r the choice of e a r. If one w ere to te s t p e rso n s
w ith u n ila te ra l h e arin g lo sse s, fo r exam ple, it would be possible
that the choice of e a r would affect the au ditory flu tte r frequency
th resh o ld .
Since th is study w as undertaken at a h o sp ital fo r the purpose
of g ath erin g n o rm ativ e d ata fo r c lin ic a l testin g , c e rta in rec o m m e n d a
tions need to be m ade fo r th is application. F ir s t, a descending
m ethod se em s p re fe ra b le b ecau se it is m ore se n sitiv e to age
differen ces and is e a s ie r to te s t than an ascending m ethod. Second,
the use of high sound in te n sitie s should be continued to guard ag ain st
d ifferen ces a ris in g due to p e rip h e ra l auditory conditions. T hird, a
sound-tim e ra tio of 75 p e r cent should be em ployed as it is
sig n ifican tly d ifferen t from the o th er two te ste d in th is study.
Im plications fo r F u rth e r R e se a rc h
The im p licatio n s to be d eriv ed from th is d isse rta tio n fa ll
into two c a te g o rie s: ex p erim e n tal and th e o re tic a l. T h ere w ere a
58
larg e num ber of ex p erim e n tal d ata which re q u ire fu rth e r v e rific a
tion, and th ere a re s e v e ra l o th er th e o re tic a l p o ssib ilitie s which
could be explored.
Among the e x p erim e n tal data, the m o st significant
v ariab le fo r fu rth e r investigation should be v a ria b ility due to age.
M ore r e s tric te d study should be done to exam ine m ore c ritic a lly
the c o rre la tio n betw een age and flu tte r th resh o ld , with age as the
only v a ria b le , holding the four o th er v a ria b le s co n stan t.
The m a tte r of psychophysical m ethod, of p rim e im portance
in th is study, b e a rs fu rth e r investigation. The two m ethods of
lim its d e sc rib e d h e re in should be com pared ag ain st o th er m ethods
on the sam e su b je cts. The p o ssib ility should be co n sid ered that the
ascending o r descending technique is m ore like som e o th er m ethod
than the two techniques a re like each o th er.
The c lin ic a l stu d ies to follow a re obvious. The flu tte r
th resh o ld should be exam ined am ong v ario u s clin ical e n titie s.
O rganic b ra in d is o rd e rs have been shown to be sen sitiv e to visual
flic k e r, and it would be in te re s tin g to explore th is rela tio n sh ip in
the au d ito ry a re a . The use of flu tte r in audiom etry would be another
in te re stin g a re a of investigation, and, indeed, should be studied to
find the re la tio n sh ip betw een flu tte r th resh o ld s and au d io m etric
th re sh o ld s fo r v a rio u s hypacuses, since the p re s e n t study elim in ated
59
su b je cts who had a h isto ry of n eu ro lo g ical o r otological d ise a se .
T h e o re tic a l c o n stru c ts o th er than the ones d isc u sse d h e re
should lead to d ifferen t fo rm u latio n s of the flu tte r phenom enon.
N eu ral function under conditions of flu tte r m ight also prove to be a
fru itfu l a re a of study fo r the n eu rophysiologist. P sychophysiological
c o n sid eratio n s need to be in v estig ated to exam ine the p ercep tu al
p ro c e ss involved; fo r exam ple, th ere a re som e in te re stin g concepts
of G e sta lt th eo ry which m ight apply (field, tra c e , e t c . ).
The p ro b lem s a sso c ia te d with the study of auditory flu tte r are
ju st being re a liz e d . A g re a t deal of re s e a r c h is re q u ire d . The
psychophysical th eo ry of sig n al d etectab ility provided an in te re stin g
approach to the m a tte r, although it was c e rta in ly not the only one
a v ailab le. We a re as y et ab eced arian about flu tte r, and th ere is
m uch to le a rn .
A P P E NDIXE S
61
A P P E N D I X A
GRASON-STADLER NOISE AUDIOMETER TYPE 830
AS DESCRIBED IN LITERATURE O F
THE MANUFACTURER DATED
FEBRUARY 1953
(NOT INCLUDING MODIFICATIONS)
G e n era l D e sc rip tio n : The Model 830 N oise A udiom eter is an in s tru
m ent containing a "w hite" noise g e n e ra to r and an e le c tro n ic
sw itch. It w ill tu rn noise on and off at v ario u s re p e titio n
ra te s and se v e ra l duty cy cles. A new ly-designed, s e lf-
balancing c irc u it in the e le c tro n ic sw itch e lim in a te s the
sw itching voltage from the output. T his fe a tu re plus a
high on-off ra tio m akes the in stru m e n t ideally suitable to
noise fusion ex p erim e n ts.
R epetition R a te s: 8 to 650 cy cles p e r second in 3 ra n g e s. A
c a lib ra te d v e rn ie r co n tro l with a range sw itch of X I, X3, and
X10.
N oise S p ectru m : 20 to 20, 000 cy cles p e r second.
R is e -F a ll T im e : L e ss than 50 m ic ro se co n d s.
O n-O ff R atio : No. 1-90 p e r cent on
No. 2 - 75 p e r cent on
W ith sw itch to tu rn noise on o r off m anually.
Output A tten u ato r: 3 db. p e r ste p . A to ta l of 10 ste p s w ith the next
to the la s t step giving 6 db. and the la s t step infinite atten u a
tion.
O utput: P erm o flu x PD R -8 earphones with #1505 e a r cushions. The
in stru m e n t w ill d e liv e r a m axim um sound p re s s u re lev el of
90 db. to the phones.
Im pedance: 500 O hm s nom inal output.
C a se : The in stru m e n t is supplied on a ra c k panel 7" by 19".
P o w er R e q u ire m e n ts: 117 V A. C. 50 to 60 cy cles w ith in te rn a l
voltage re g u la to rs to m inim ize in te rfe re n c e fro m e x te rn a l
flu ctu atio n s.
62
A P P E N D I X B
AUDIOMETRIC STANDARDS
G roup
F req u en cy
250 500 lkc 2kc 3kc 4kc 6kc 8kc
I 15 10 10 10 10 10 10 15
n 15 10 10 10 15 15 15 20
m 15 10 10 15 20 20 25 25
IV 20 15 15 20 25 30 40 40
V 20 15 20 30 40 45 50 55
Note: A ll e n trie s a re in decibels re 0. 0002 m ic ro b a r.
AUDIOMETRIC RESULTS
G roup
F req u en cy
250 500 lkc 2kc 3kc 4kc 6kc 8kc
I 1.83 1. 83 -0 .8 3 -3. 92 -3. 83 -4. 16 -1. 75 -2. 00
n 6 . 33 5. 17 3. 08 2. 50 3. 08 4. 50 7. 17 4. 16
hi 10. 25 8. 08 5. 75 4. 08 4. 58 4. 83 6. 00 7. 33
IV 10. 01 11.08 9. 58 11. 16 13. 33 16. 83 21.67 25. 50
V 11.67 10. 16 10.68 15. 08 20. 50 25.41 28. 58 30. 16
N ote: A ll e n trie s a re fo r both e a r s and a re in d ecib els re 0. 0002
m ic ro b a r.
63
A P P E N D I X C
EQUATIONS FO R ANALYSIS O F VARIANCE *
a - i xi*>2-Tsj
L i=ij=i k=i ->
r b a c
L j=li=l k=l
I X^ )2- TS
L k=li=l j=l
A B * sfcrf-I X‘IJ W*-T B }
L i=l j=lk=l
a c - f ' i v * - ™ }
L i=l k=li=l J
b c ■ bc i
L j= l k= 1 i= 1
R esid u al ■ T - (A+B-f-C+AB+AC+BC)
t ' t o t a i ■ , i i i v ' - i
i= 1 ]= 1 k= 1
- (A+B)
- (A+C)
- (B+C)
* The equations shown on th is page re p re s e n t the fo rm u sed in the
a n aly sis of v arian ce; in th is study th e re w ere five dim ensions.
B I B L I O G R A P H Y
B I B L I O G R A P H Y
A. BOOKS
D avenport, W ilbur B ., J r . , and W illiam L. R oot. An Introduction
to the T heory of Random S ignals and N o ise . New Y ork:
M cG raw -H ill Book Com pany, In c ., 1958.
H e lstro m , C a rl W. S ta tistic a l T heory of Signal D etectio n . New Y ork:
P erg am o n P re s s , 1960.
Law son, Ja m e s L . , and G eorge E . U hlenbeck. T h resh o ld S ig n a ls.
New Y ork: M cG raw -H ill Book Com pany, I n c ., 1950.
L ic k lid e r, J. C. R. "B asic C o rre la te s of the A uditory Stim ulus, "
Handbook of E x p e rim e n ta l Psychology, ed. S. S. Stevens.
New Y ork: John W iley and Sons, In c ., 1951
_______________. "A uditory F re q u en c y A nalysis, " Inform ation
T heory, ed. E . C. C h e rry . New Y ork: A cadem ic P r e s s ,
1956.
_______________. "T h ree A uditory T h eo ries, " P sychology: A Study
of Science, ed. S. Kock. New Y ork: M cG raw -H ill Book
Com pany, I n c ., 1959.
O dell, C . Introduction to E d u catio n al S ta tis tic s . New York:
P re n tic e -H a ll, 1948.
P e te rs o n , A rnold, and Leo B eran ek . Handbook of N oise M e a su re
m ent, second ed. C am bridge, M a ssa c h u se tts: G e n era l R adio
Com pany, 1956.
S tevens, S. S. "M athem atics, M easu rem en t, and P sy ch o p h y sics, "
Handbook of E x p e rim e n ta l P sychology, ed. S. S. Stevens.
New Y ork: John W iley and Sons, I n c ., 1951.
W ever, E rn e s t G. T heory of H e a rin g . New Y ork: John W iley and
Sons, In c ., 1949.
65
66
B . A R T I C L E S AND P E R I O D I C A L S
B eh ar, I . , and W. Be van. "A nalysis of the P rim e P sy ch o p h y sical
Judgm ent, " P e rc e p tu a l and M otor S k ills, X (1960), 82.
C hapm an, L . , D. Sym m es, and W. H alstead, "A uditory F lu tte r
F u sio n in P a tie n ts w ith C o rtic al A b la tio n s," Jo u rn a l of
C om parative and P hysiological Psychology, XLVIII (1955),
421-425.
C histovich, L . A. "D iscrim in atio n of the T im e In terv a l B etw een Two
S hort A coustic P u lse s, " Soviet P h y s ic s - - A co u stics (T ra n sla tio n
of A k u stich esk ii Z h u rn a l), V (1960), 493-497.
G a rn e r, W. R. "A uditory T h resh o ld s of S hort T ones as a F unction
of R epetition R a te s, " Jo u rn al of the A coustical Society of
A m e ric a , XIX (1947), 600-608.
G reen , D. M ., T . G. B ird sa ll, and W. P . T an n er, J r . "Signal
D etection as a Function of Signal Intensity and D uration, "
Jo u rn a l of the A coustical Society of A m erica, XXIX (1957),
523-531.
H irsh , I ra J. "A uditory P e rce p tio n of T em p o ral O rd e r, " Jo u rn a l
of the A co u stical Society of A m erica, XXXI (1959), 759-767.
L ic k lid e r, J. C. R. "A Duplex T heory of P itc h P e rce p tio n , "
E x p e rie n tia , VII (1951), 128-134.
M ille r, G eorge A. "The P e rc e p tio n of S hort B u rsts of N oise, "
Jo u rn a l of the A coustical Society of A m erica, XX (1948),
160-170.
_______________and W alte r G. T ay lo r. "The P e rc e p tio n of R epeated
B u rs ts of N oise, " Jo u rn a l of the A coustical Society of A m erica,
XX (1948), 171-182.
P o llack , Irw in. "A uditory F lu tte r, " A m erican Jo u rn a l of
Psychology, LXV (1952), 544-554.
Sym m es, D ., L . Chapm an, and W. H alstead . "The F u sio n of
In te rm itte n t W hite N oise, " Jo u rn al of the A coustical Society of
A m erica, XXVEt (1955), 741-748.
67
T anner, W. P . , J r . , and T. G. B ird s a ll. "D efinitions of d* and ^
as P sychophysical M e asu res, " Jo u rn a l of the A coustical
Society of A m erica, XXX (1958), 922-928.
T hurlow , W ., and R. Bowm an. "T h resh o ld fo r T h erm al N oise as
a F unction of D uration and In terru p tio n R ate, " Jo u rn a l of the
A coustical Society of A m erica, XXIX (1957), 281-283.
C . R E P O R T S
Sim onson, E rn s t, and Jo sef B rozek. F lic k e r F u sio n F re q u en c y ,
B ackground and A pplications, P ro je c t 21 32 004, R ep o rt No. 2.
Randolph A ir F o rc e B ase, T exas: USAF, A ir U niversity,
School of A viation M edicine, 1953.
T an n er, W. P ., J r . A T heory of R ecognition. T echnical R eport
No. 50, E le c tro n ic D efense G roup, D ep artm en t of E le c tric a l
E ngineering, U n iv ersity of M ichigan, May, 1955.
D . U N P U B L I S H E D M A T E R I A L
L aw rence, L ois C. "A uditory F lu tte r F u sio n as a M easure of
C e n tra l E ffe ctiv en e ss. " U npublished d o cto ral d isse rta tio n ,
C o rn ell U n iv ersity , 1956. D isse rta tio n A b s tra c ts , XVI
(1956), 1724-1725, #18277.
Linked assets
University of Southern California Dissertations and Theses
Conceptually similar
PDF
Teaching Operative Dental Technics Via Television: An Experimental Inquiry
PDF
An Experimental Study Of Several Methods Of Teaching Basic College Speechcourses With Emphasis On Conservation Of Teachers' Time And Varying Class Size
PDF
An Experimental Study Of Intelligibility Thresholds Of Hypacusic Adults Using Forced-Choice And Yes-No Techniques
PDF
An Experimental Investigation Of Repression Of The Auditory Perception Ofdisturbing Words As Indicated By Verbal And Electrodermal Responses
PDF
An Experimental Study Of Auditory Thresholds Of Adults For Warble Tone, Pure Tone, And Recorded Speech
PDF
An Experimental Comparison Of Spoken Communication Developed Individually and Interindividually
PDF
An Experimental Study Of The Effects Of Interaural Temporal Delays And Intensity Differences On Intracranial Localization Of Spondee Words
PDF
An Experimental Study Of The Effect Of Listener Feedback On Speaker Attitude
PDF
Some Relationships Between Auditory Reaction Time And Number Of Oscillations Of Fixed Frequency Bekesy Tracings
PDF
An Experimental Study Of Effects Of Interest And Authority Upon Understanding Of Broadcast Information
PDF
An Experimental Study Of The Ability Of Lay Judges To Distinguish Betweentypescripts Of Individual Idea Development And Group Idea Development
PDF
An Experimental Study Of The Influence Of Subliminal Cue Words On Audience Responses To A Filmed Speaker'S Sincerity, Effectiveness, And Subject Matter
PDF
An Experimental Study Of The Retention And Comprehension Of Poetry Resulting From Silent Reading And From Oral Interpretation
PDF
An Experimental Study Of The Accuracy Of Experienced And Inexperienced Speakers In Identifying Audience Behavior As Indicative Of Feelings Of Agreement, Indecision, Or Disagreement
PDF
A Historical Study Of Speech Education At The University Of Southern California (1880 Through 1950)
PDF
An Experimental Study Of An Application Of Game Theory To The Selection Of Arguments By College Debaters
PDF
An Experimental Study Of The Effect Of Punishment Of The Expectancy To Stutter On The Frequency Of Subsequent Expectancies And Stuttering
PDF
An Experimental Application Of 'Cloze' Procedure As A Diagnostic Test Of Listening Comprehension Among Foreign Students
PDF
An Empirical Study Of Classroom Teaching Of Ethics In Beginning College Public Speaking Courses
PDF
An Experimental Study Of Relationships Between Self-Concepts Of Fourth And Eighth Grade Stuttering And Non-Stuttering Boys
Asset Metadata
Creator
Gerber, Sanford Edwin
(author)
Core Title
An Experimental Study Of Factors Influencing The Perception Of Auditory Flutter
Degree
Doctor of Philosophy
Degree Program
Speech
Publisher
University of Southern California
(original),
University of Southern California. Libraries
(digital)
Tag
OAI-PMH Harvest,Theater
Language
English
Contributor
Digitized by ProQuest
(provenance)
Advisor
Garwood, Victor P. (
committee chair
), Dickens, Milton (
committee member
), Harvey, Herman M. (
committee member
)
Permanent Link (DOI)
https://doi.org/10.25549/usctheses-c18-253672
Unique identifier
UC11358685
Identifier
6203729.pdf (filename),usctheses-c18-253672 (legacy record id)
Legacy Identifier
6203729.pdf
Dmrecord
253672
Document Type
Dissertation
Rights
Gerber, Sanford Edwin
Type
texts
Source
University of Southern California
(contributing entity),
University of Southern California Dissertations and Theses
(collection)
Access Conditions
The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...
Repository Name
University of Southern California Digital Library
Repository Location
USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA