Pure tone pitch perception and low-frequency hearing loss
Christopher Turner
Departmentof SpeechPathologyand•ludiology,7•400, 11044-82•lvenue,UniverSity
of•llberta,Edmonton,
•11berta T6G OT2, Canada
Edward
M. Burns
Departmentof •ludiologyand SpeechSciences,
PurdueUniversity,WestLafayette,Indiana 47907
David A. Nelson
HearingResearch
Laboratory,Departmentof Otolaryngology
andDepartmentof Cornrnunication
Disorders,
Universityof Minnesota,Minneapolis,Minnesota55455
{Received6 July 1982;acceptedfor publication17 November 1982)
Pitch perceptionfor puretoneswasinvestigated
in a groupof listenerswith low-frequency
sensorineural
heatingloss.Pitchjudgmentsfrom eachlistenerwerecomparedwith resultsfrom
psycho-acoustic
taskswhichprovideinformationon the "place"of cochlearresponse.
The pitch
measuresemployedwere:{1}binauralpure-tonepitch matchingin a listenerwith unilateral
heatingloss,{2)octavejudgmentsin listenerswith musicalability,and{3)pitch-intensity
functionsin otherlisteners.Cochlearplaceof response
wasinferredfrom psychophysical
tuning
curves{PTC's).Two distincttypesof PTC's for low-frequency
probetoneswereobserved.
Three
listenersdemonstrated"abnormallytuned"PTC's. For theselistenersthe frequencies
that were
mosteffectiveat maskingtheprobewereconsiderably
higherthantheprobefrequency.
The three
remaininglistenersdemonstrated"normally tuned" PTC's. Listenerswith abnormallytuned
PTC's weresuspected
of havinganextremelyabnormalplaceof response
for low-frequency
tones;
thisresponsepatternbeinglocatedmoretowardthe baseof the cochleathan in the listenerswith
normallytunedPTC's. Sensitivitythresholdsmeasuredin the presence
of high-passmasking
noisesupportedthis hypothesis.
Smallpitch-frequency
irregularitieswereobservedin many
listeners,althoughtheywerenot consistently
relatedto theinferredplaceof response
for that
frequency.The individuallisteners'pitchjudgmentsfailedto distinguish
betweentwo typesof
PTC's. In particular,listenerswho demonstrated
abnormallytunedPTC's did not exhibit
correspondingly
largepitchirregularities.Theseresultsare difficultto explainon the basisof a
classical"place"theoryof pitch perception.
.
PACS numbers:43.66.Sr,43.66.Ba,43.66.Hg [JH]
INTRODUCTION
Currenttheoriesconcerningthe pitchof complextones
{Goldstein,1973;Wightman, 1973;Terhardt, 1974}propose
a multistagepitch processor;
incomingcomplexstimuliare
subjectedto an initial analysiswhichyieldsthe frequency{or
pitch}of the resolvedstimuluscomponents.
This patternof
components
issentto a centralprocessor
for identificationas
a single"best fitting" fundamentalpitch. This theoretical
work has primarily emphasizedthe nature of this central
processor
anditsdecision-making
process.
The relevantcoding of the inputsfrom the cochlearemainsunanswered.It is
this question,the encodingof the pitch of singlepure tones,
which will be the topic of this report.
The classical"place" theoryof pitch perceptionrelates
the pitchof a pure-tonestimulusto somespatialcharacteristic of its pattern of neural activity acrossthe cochlea.Accordingly,differingplacesof stimulationfor pure tonesof
differentfrequencieswill lead to differentpitch sensations
{Bekesy,1960;Zwicker, 1970}.In contrastwith the place
theory, an alternativemechanismfor the peripheralencoding of pitch has traditionallybeenproposed,which relates
the pitch of pure tones to the temporal pattern of neural
firings,thistemporalpatternbeinglinkedto thefrequencyof
the pure-tonestimulus{Wever, 1949;Goldsteinand Srulo966
J. Acoust.Soc. Am. 73 (3), March 1983
vicz, 1977}.Sincemany formsof sensorineural
hearingloss
havebeenlinkedto lesionsof sensoryreceptorswithin the
cochlea,the useof certaintypesof hearing-impairedlistenerswouldseemto offeran opportunityto studypitchperception in listenerswith abnormalspatialpatternsof cochlear
stimulation. The present experimentswill investigate
whetheror not suchlisteners'pitch judgmentsfollow the
abnormalplacecuesavailableto the auditory system.
Psychoacoustical
maskingdata obtainedfrom human
listenersareassumed
to displaythe spatialresponse
pattern,
with the maskedthresholdsof test stimuli surroundinga
pure-tone or narrow-band masker,indicatingthe relative
shapeand positionof the responsepattern {Plomp, 1976}.
This concepthas been developedextensivelyby Zwicker
{1970}as the "excitationpattern" of a pure tone. Thus the
classicalmaskingpatternsof Wegeland Lane{1924}andthe
variousrefinementsupon this basic paradigm{Egan and
Hake, 1950;Vogten, 1974; and Houtgast, 1974}are theorized to representa relative displayof the neural activity
resultingfrom the stimulusof interest{inthisparadigm,the
maskeris the stimulusof interest}.The tonotopicpatternof
cochlearorganizationis reflectedby maskingpatternscenteredaboutthe maskerfrequency,andasthe maskerintensity is increased,the responsepatternspreadsnonsymmetri-
0001-4966/83/030966-10500.80
¸ 1983 AcousticalSocietyof America
966 •
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cally,with a greaterspreadtowardhigherfrequencies
(i.e.,
frequency,in somecases,more than two octavesabove.
more basalsensoryunits).
In contrastwith classical
maskingpatterns,thepsycho-
This secondtype of PTC suggested
to Thorntonand
Abbasthat the detectionof the low-frequency
probewas
occurringat a placenormallyassociated
with a response
patternfor highfrequencies.
Theseauthorsproposed,
for
listeners
with abnormallytunedPTC's,thatsensory
unitsat
theapicalendof thecochlea
(thoseunitswhichareusedby
physicaltuningcurves(PTC)paradigmemploysa lowsensation level probe that is held constantwhile the masker is
varied.If it is assumedthat the maximallyeffectivemasker
frequency
(MMF)occurswhenthemasker's
neuralresponse
patternis centeredoverthe probe'sresponse
pattern,we arrive at the conclusionthat the PTC "tip" indicatesthe relative placeof maximumneuralresponse
for a givenprobe
tone.The locationof PTC tipsalongthe frequencydimensionare assumedto correspondto the spatiallocationof
eachtone'sresponsepattern alongthe basilarmembrane,
with tonesof low frequencynormallyhavinga PTC tip locatedat lowfrequencies
(apicallocation)andtonesof higher
frequency
havingtheirPTC tip at higherfrequencies
(basal
location).In addition,the high-frequency
sideof the PTC is
assumed
to indicatetherelativepositionof theapicaledgeof
theprobe'sresponse
pattern,sincemaskerswith frequencies
higherthan this sideof the PTC will be ineffectivein maskingthemoreapicalregionsof the cochlea(i.e.,thoseregions
responding
to the lowerfrequencyprobetone).
PTC's from mostlisteners(normal-hearingand hearing-impaired)
tendto indicatea normalplaceof response
for
the probetone. Althoughsmall discrepancies
(up to 6%)
betweentheMMF andtheprobefrequencyin simultaneousmaskedPTC's have been noted by Vogten (1974, 1978;
Moore, 1978),thesediscrepancies
wouldappearto berelated
to thesuppression
effectspresentin a simultaneous-masking
paradigm,andtherefore,not potentiallyrelatedto the pitch
sensation
of a pure tone.Moore (1981)reporteddiscrepanciesbetweenMMF andprobefrequency
in a forward-masking paradigmas large as 3% (at 1000 Hz). He showeda
significantrank-order correlationof these discrepancies
with thelisteners'pitchsensations.
The issueof pitchsensation and its relationto the PTC, however,will mostlikely
remainunanswered
by research
involvingonlylistenerswith
smallMMF-probefrequency
discrepancies,
sincetheirregularitiesare not largewhencomparedwith the precisionof
PTC measurements.
In contrast with the resultsdescribedabove, two recent
reportsof PTC's from heating-impairedlistenersdemonstratestrikingdiscrepancies
betweenthe probefrequency
and the MMF or frequencylocationof the high-frequency
sideof thePTC. ThorntonandAbbas(1980)andGoldstein
etal. (1982)havemeasured
PTC's(simultaneous
masking)
in
listenerswith low-frequencysensorineuralheating loss.
They demonstratedtwo typesof PTC's for low-frequency
probes.Subjectswith a maximummaskingfrequencyat or
neartheprobefrequencyexhibitedthe normalrulesof masking, that is, little maskingoccurredfor maskersabovethe
probe frequencyand maximum maskingoccurredwhen
maskerfrequencyequaledprobefrequency.Sucha PTC will
betermeda "normallytunedPTC." The secondtypeof PTC
found by theseresearchers,
termed "abnormallytuned,"
showeda maximummaskingfrequencythat waslocatedat a
frequency
considerably
higherthantheprobefrequency.In
addition,the steephigh-frequencysideof the PTC for the
abnormallytuned PTC's was locatedfar abovethe probe
967
J. Acoust.
Soc.Am.,Vol.73, No.3, March1983
normal-hearinglistenersto detect threshold-levellow-fre-
quencysignals)
weredestroyed
or absent.
At thehighersignal levelsrequiredto reachthreshold
in theseheating-loss
listeners,
thedetection
of theprobewasdueto sensory
units
located
moretowardthebaseofthecochlea.
Thus,although
the mechanicalvibrationpattern of the basilarmembrane
waspresumedto be essentiallynormalin theselisteners,the
neuralresponse
to the vibrationoccurredonly at cochlear
regionslocatedmore basalthan normal.
Indeed,the abnormallytunedPTC's reportedby these
researchers
resemble
the singleunit maskedphysiological
tuningcurvesof Bauer(1978)for high-frequency
CF (basal
location)neurons.When the maskerlevelsrequiredto decreasethe neuralresponse
to a low-frequency
probetone
wereplottedasa functionof frequency,this neural-masked
tuning curve showeda distinct MMF at the CF of the neuron, ratherthanat theprobefrequency.Thusthe mosteffec-
tive maskerat thisneuron'splace(basallocation),for any
probefrequency,wasa high-frequency
maskerat the neuron'sCF. Santiet al. (1982)demonstrated
that neitherbehavioral audiograms
nor AP audiograms
coulddistinguish
betweenanimalswith completemidcochleahair celllossand
thosewith at leastsomepresentsensory
elements.
Singleunit studies showed that neurons located basal to the hair
celllosswereresponding
to the lowerfrequencytonesand,
therefore,musthavebeenresponsible
for the behavioralor
AP responses.
If human subjectswith lesionssuchas this
couldbe identified(thoselistenerswith completeapicalor
midcochlea
haircelllossversusthosewithmerelydamaged
apicalsensory
units),wewouldhaveanopportunity
to separate the placeversustiming cuesof a pure-tonestimulus.
Thoselistenerswith apicalhair celllosswouldhavea neural
responsepattern maximum for low-frequencytones at a
placenormallyassociated
with higher-frequency
tones.If
theinterpretation
of theabnormallytunedPTC'sput forth
by Thornton and Abbas is correct, the PTC would seemto
offera noninvasive
methodof identifyingsuchlisteners.Listeners'judgmentsof pitch couldthen be comparedto the
placeof response
indicatedby the PTC asa testof the classicalplacetheoryof pitchperception
for puretones.
I. DESCRIPTION
OF LISTENERS
A totalof sixlistenerswith low-frequency
hearingloss
wereusedin theseexperiments.
Listeners
rangedin agefrom
28 to 70 yearsof age;all werefemaleexeptfor JN. Standard
audiometrywasperformedon all listeners
duringtheir initial visit to the laboratory.In all cases,the thresholdsobtainedby air conductiondid not differfrom thoseby bone
conductionby morethan 10 dB, and in nearlyall casesthe
air-bonegap was 5 dB or less;this suggests
that all losses
wereprimarilysensorineural
in origin.None of the listeners
exhibitedexcessive
tonedecay(methodof Olsenand NoffTurnereta/.: Pitchandlow-frequency
hearingloss
967
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singer,1974).One of the six listeners,KB, was diagnosed
earlier in life as havingMeniere'sDisease,and did report a
previoushistoryof vertigoattacksand tinnitus.Her thresholds remainedstablethroughoutthe courseof theseexperiments.The hearinglossin the other listenerswasattributed
to geneticcauses.All listenershad very good speechdiscrimination scores(86% or better on NU-6 recordedword
lists)and reportedlittle difficultyin conversationalsituations,althoughlistenerDR requireda heatingaid in everyday activities.Exceptfor the unilateralheating-loss
listener,
MA, all measurementswere performedin each listener's
more sensitiveear. ListenerJN had no measurablehearing
in his nontestear. Listeners'sensitivitythresholdsreported
in the followingexperimentsweregatheredwith a four-alternativeforced-choice(4AFC)adaptive procedureusing200-
tuned PTC's were not the result of artifactsin a subject's
performance.In addition,simultaneousmaskedPTC's were
alsoobtainedfrom a few listenersin orderto comparefindingswith thoseobtainedby the forward-masked
procedure.
A. Methods
1. Forward-maskedpsychophy$icaltuningcurves
A 200-mspure-tonemaskcrwith 10-msrise-fall times
wasfollowedby a 20-msprobetone.The temporalseparationbetweenmaskerandprobewas2 ms.A 4AFC paradigm
wasusedfor presentation,
with the maskeralonepresented
in three intervals,and probeplus maskerin a fourth, randomly chosen,interval. The 2-up, 1-down steppingrule
guidedthemaskerlevelin an adaptiveprocedureto trackthe
71%-correctlevelof performance(Levitt, 1971).Forwardmaskedtuningcurvesweremeasuredfor probesat 250 and
500 Hz. Probe levelswere 10-15 dB abovethe pure-tone
thresholdsobtainedfor longerdurationsignals(200-ms).
This level corresponded
to a sensationlevel for the shortdurationprobeof about5 dB. Up to 12runswererequiredto
obtainasymptoticperformancefor somelisteners'PTC's.
ms pure tones.
II. EXPERIMENT
I
The PTC's of Thornton and Abbas (1980)and Goldsteinet al. (1982)wereobtainedusinga simultaneous
masking technique,and maskerlevelsof 70 to 100 dB SPL were
requiredto maskthe probe.At thesehighstimuluslevelsand
in the simultaneous
maskingcondition,the potentialfor the
productionof combinationtones,beats,or other artifacts
exists(Nelson, 1979).The detectionof thesedistortionproductscouldinfluencethe shapeof the PTC (CarneyandNelson, 1982). In the presentexperiment,a forward-masking
paradigm was employedin an attempt to substantiatethe
findingthat two classes
of low-frequencysensorineural
hearing lossexist.Listenerswerealloweda considerable
number
of practicesessions,
insuringthat maximumlevelsof performance were reached by all listenersand that abnormally
2. Simultaneous-masked
psychophysical
tuningcurves
Simultaneous-masked PTC's were measured in five lis-
teners,four of whomhad previouslycompletedthe forwardmaskedPTC experiment.Subjectstrackedthe maskerlevel
necessary
to maskthe probewith a Bekesyrecordingattenuator. The maskerwas a continuouspure tone of fixedfrequencyand the probetonewasa pulsedsignalat 250 or 500
Hz. The probeduration was 250 ms, 50% duty cyclein a
FIG. l. Psychophysical
tuning curves
(PTC's) for listenersCA and CX. Forward maskedPTC's are displayedin the
upper panelsand simultaneousmasked
PTC's are displayedin the lowerpanels.
Maskerlevelsrequiredto maskprobesat
250 Hz (n
ID) and at 500 Hz
It8
I
80
-
78
-
I
I
118j
I
I
I
I
I
I
_
(/•
/•) are plottedin eachpanel
asa functionof maskerfrequency.The
tips of the vertical arrows indicatethe
levelandfrequencyof the probe.Listeners' sensitivitythresholds( X
X)
alongwith sensitivitythresholdsfor normal hearing(0
O) are plottedbelow the PTC's.
48
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J. Acoust. Soc. Am., Vol. 73, No. 3, March 1983
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968
Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 134.84.192.102 On: Thu, 26 Dec 2013 20:39:47
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4. Simultaneous masked PTC's at 250 and 500 Hz for listener MA.
Abnormally tuned PTC's at 250 and 500 Hz (simultaneous-and forward-masked}from listenersKB and JN are
shown in Fig. 3. Both the forward-maskedand simultaneous-masked
PTC's from thesetwo listenershavehigh-freqencysideslocatedmorethan 1 octabovethe probefrequency. Each listener'sPTC's at 250 and 500 Hz sharea similar
frequencylocationfor the high-frequencyslope.Additional
PTC measuresfor 1000-Hz probesin listenersKB and JN
(notshown}had high-frequencysidessimilarto their PTC's
for the lower-frequencyprobes.This is suggestive
of a common placeof cochlearresponsefor all lower-frequencypure
tonesin theseears.Figure 4 displayssimultaneous-masked
followedby ThorntonandAbbas{1980},with the exception
that theydid not usethe Bekesytrackingmethodemployed
in thepresentexperiment,
butusedinsteada methodof limits.
B. Results
Figure1 showsPTC'sfrombothsimultaneous
andforward-maskedparadigmsfrom listenersCA and CX. These
listenersdisplaynormallytunedPTC's at 250 and 500 Hz
for both masking paradigms.Figure 2 shows forwardI
1888
250 and 500 Hz for these three listeners.
sultsweretakenasthe latter of the two runs.This procedure
waschosento replicateascloselyaspossiblethe procedure
I
588
maskedPTC's from listenerDR; thesePTC's were alsoclassifiedas normally tuned. In each of theselisteners'PTC's,
the MMF and the high-frequencysideof the tuningcurveis
locatedat or near the probefrequency.This suggests
essentially normal cochlearplacesof responsefor pure tonesof
was run twice on the 250- and 500-Hz PTC's, and final re-
I
.-.
Symbolsare the sameasfor Fig. 1.
500-msperiod(25 ms rise-decaytimes}.The level of the
probewassetto approximately5-10 dB SL. Each listener
I
2S8
Frequencu
t8000
.
S,
IqUI•TI:iNEOU•
.$K,
NjG•jubJ
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DR(LE)
FIG. 2. ForwardmaskedPTC's at 250 and 500Hz for listenerDR. Symbols
are the sameasfor Fig. 1.
118j
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•
28-
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FIG.
16888
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3. PTC's at 250 and 500 Hz for lis-
tenersKB and JN. Symbolsare the same
asfor Fig. 1.
118
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969
(Hz)
J. Acoust.Soc. Am., Vol. 73, No. 3, March 1983
Frequenc•
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Turner eta/.' Pitchand low-frequencyhearing loss
969
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PTC's at 250 and 500 Hz for listenerMA. As in the previous
figure, MA's PTC's for the two different low-frequency
probessharea commonhigh-frequencyside.The 250-Hz
PTC is clearly abnormallytuned and is suggestive
of an abnormalplaceof response
for puretonesbelow500Hz in this
ear.
'
The presentresultsconfirmthe recentliteraturereports
that listenerswith low-frequencyhearinglosscanbedivided
into two groupson thebasisof their PTC's for low-frequency
probes.Both forward- and simultaneous-masked
PTC's resulted in identical classifications in the four listeners where
both paradigmswereemployed.GrosslyabnormalMMF's
were not readily apparentfor all abnormallytuned PTC's;
the PTC's of listener KB in particular were rather fiat in
shape.This result is similar to that reportedby Thornton
and Abbas (1980},in which only somelistenersdisplayed
very distinct MMF's. Although this findingmay havebeen
due to the choiceof maskerfrequencies,it is also possible
that it indicatesa broaderarea of maximum responseto the
low-frequencyprobetones.Although listenerKB did show
distinctMMF's in resultsfrom earlierexperimentalsessions,
repeated practice sessionsresulted in the flatter PTC's
shownin Fig. 3.
As proposedby ThorntonandAbbas(1980},the abnormally tunedPTC's suggestthat probedetectionin theselistenersis occurringat a placeon the basilarmembranethat is
located more basal than normal, due to nonfunctional or
absentsensoryunits at the apex.The shapeof the low-frequencythresholdcurvein theselistenerswouldthenbe the
resultof the highersignalintensitiesneededto stimulatethe
remainingfunctionalsensoryunitsas stimulusfrequencyis
decreased.The slopeof 15 to 25 dB per oct for the lowfrequencysensitivitythresholds
in theabnormallytunedlistenersdoescorrespondto the low-frequencyslopeof singleunit neural tuning curvesfor mid-frequencyneuronsof the
cat (Kiang and Moxon, 1974}.Although quantitativecomparisonsbetweenthe presentdata and that from animals
shouldbe made with caution,it is temptingto explain the
apparentcorrespondence
of audiogramslopeswith the occurrenceof abnormallytunedPTC's by speculatingthat the
low-frequencythresholdsare the resultof the sensitivityof
mid-cochleaneurons.The two ears with abnormally tuned
PTC's at 250 Hz from the study by Thornton and Abbas
(1980} also showedthis characteristicslopeof the audiogram.However,the two earsin their study.withabnormally
tuned PTC's
at 500 Hz did not show this characteristic
slope,evenfor frequencies
just abovethe 500-Hz probe.
III. EXPERIMENT
2
The interpretationof the abnormallytuned PTC's in
experiment1 wasthat suchPTC's werethe resultof an abnormalplaceof response
for the low-frequencyprobetones.
In orderto substantiate
thishypothesis,thresholdsfrom listeners with normally and abnormally tuned PTC's were
measured
in the presence
of high-frequency
maskingnoise.
Those listenerswith normally tuned PTC's {implyinga responseto low-frequencytonesfrom functionalapical sensory units} should show little or no downward spreadof
maskingas a resultof high-frequencynoise;listenerswith
970
J. Acoust.Soc. Am., Vol. 73, No. 3, March 1983
abnormallytunedPTC's (implyinga response
onlyfrombasal sensoryunits)shoulddisplayan abnormalshift of lowfrequency thresholdsin the presenceof high-frequency
maskingnoise.
Results from normal-hearing listeners (Bilger and
Hirsh, 1956)andsensorineural
hearing-loss
listeners(Jerger
et al., 1960;Keith and Anderson,1969)haveshownthat no
maskingfor low-frequency
tonesby high-or mid-frequency
noise bands occurs until the overall level of the masker is at
least80-100-dB SPL. Low-frequencythresholdshiftsfrom
high-frequency,
high-levelmaskershavebeentermed"remote masking"and havebeenattributed to the production
within the cochlea of distortion products related to the
maskerenvelope(Deatherageet al., 1957),or to the effectof
the middle-ear reflex. In contrast with remote masking,
thoselistenerswith abnormally tuned PTC's should show
thresholdshiftsfor frequenciesbelow the passbandof the
noiseat substantiallylower maskerlevels.
A. Methods
Five listenersfrom experiment1participatedin thepresentexperiment,two with abnormallytunedPTC:s (KB and
JN} and three with normally tuned PTC's (CA, CX, and
DR}. Becausethe high-frequencysidesof the abnormally
tuned PTC's at 250 and 500 Hz for KB and JN were located
between1000and 2000 Hz, the maskingnoisespectrumwas
chosento shift thresholdsat 1000Hz and above,while spectral energyat 250 and 500 Hz wasundesirable.The masking
noiseemployedwas a bandpass-filtered
white noisewith a
low-frequencycutoff of 1400 Hz, high-frequencycutoff of
3000 Hz, and filter slopesof -- 18 dB per oct. Four levelsof
maskingnoisewere employed,with spectrumlevelswithin
the passbandof 35-, 45-, 55-, or 65-dB SPL. This correspondedto overall maskerlevelsof 67-, 77-, 87-, or 97-dB
SPL. Maskedthresholdsweremeasuredusinga 4AFC adaptive procedure.
B. Results
Masked thresholdsfor frequencieswithin or near the
passband
of the noise(1000,2000, 3000,and 4000 Hz) were
elevatedto levelswhich were,on the average,in agreement
with criticalratio predictions.Maskingof lowerfrequencies
(250 and 500 Hz) by the high-frequencynoiseis plotted in
Fig. 5. Although the listenerswith normally tuned PTC's
(CA, CX, and DR} showthresholdshiftsat the highermasker levels,noneshowshiftsgreaterthan 2 dB until the masker
levelreaches87-dBSPL (55-dBspectrumlevel).This shiftof
low-frequencythresholdsat high masker levels resembles
the remotemaskingdiscussed
previously.
ListenerJN's low-frequencythresholdsare shiftedfor
all maskerlevels.The growthof maskingfor JN occursat a
rate of approximately1 dB for every 3 dB of maskerlevel
increase.This slopeof lessthan unity is consistent
with JN's
detectionof low-frequencytonesat a higher-frequencyregion of the cochlea.Due to an asymmetricgrowth of responsepattern in the cochleaas the intensityof a low-fre-
quencytoneis increased,
anincrease
of thelow-frequency
tonelevelwill causea greaterincreaseon the basalsideof the
Turner et al.: Pitchand low-frequencyhearingloss
970
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ß
ß
25
o
JN
KB
ß
CX
ß
ß
CA
DR
ß
JN
CX
ß CA
ß " DR
FIG. 5. Amount of maskingat
15
250 and 500 Hz as a function of
the spectrum level within the
passbandof the maskingnoise.
o 10
•
5
I
Qmet
SPECTRUM
35
LEVEL
45
55
65
OF NOISE (dB SPL)
SPECTRUM
response
patternthanat thepeak.Thisasymmetric
growth
of response
is reflected
in thenormal-listener
masking
data
of EganandHake{1950}andin theexcitation
patterns
of
Zwicker{1970}.In listenerJN, a 1-dBincrease
in thephysicalintensityof a low-frequency
tonewouldrequirea 3-dB
increaseof the high-frequency
maskerto maskthe active
fibersat thehigh-frequency
place.Theseresultssuggest
that
listenerJN hasa complete
destruction
ofactivesensory
units
at theapexof thecochlea,
andresponds
onlywiththesensoryunitslocatedtowardthebase.Thisresponse
areamay
be relatedto the verydistinctMMF's seenin his PTC's at
The other listenerwith abnormallytuned PTC's, KB,
showsa 5-10-dB shiftin low-frequency
thresholds
for the
35-dBSPLspectrum
levelmasker,
butlittleornoincrease
in
masking
asthemasker
levelisincreased.
Thissuggests
that
whenlow-frequency
tonesareraisedto a sensation
levelof
5-10 dB,anotherpopulation
of fibers,possibly
damaged
fbersat thecochlear
apex{e.g.,LibermanandKiang,1978},
begins
tocontribute
totheresponse.
ThePTC'sofKB at250
and 500 Hz do not show distinct MMF's as did those of
listenerJN; insteadthey suggesta broadermaximumresponseareafor low-frequency
tones.
3
Theresultsof experiments
1 and2 haveobvious
implicationsfor pitchmeasurements
if theplaceof cochlear
re-
sponse
is indeedtherelevant
parameter
for thecodingof
pure-tone
pitch.Themostclearcut
example
is thatof the
unilaterally
impairedsubject,
MA. The PTC'sfor herimpairedcar(Fig.4) showfairlysharptuningcurves
withan
MMF in theareaof 500 Hz for probetonesof 250 and500
Hz. Theimplication
of thisresultisthat,for frequencies
at
andbelow500Hz, MA isresponding
to a commonplaceof
cochlearresponse
locatedin the areanormallytunedto
about500Hz. The obviouspredictionthen,basedon place
theory,is thatMA will hearall tonesbelow500Hz in her
impairedearashavinga pitchroughlyequivalent
to a 500Hz tonein hernormalear.Thispredictionshouldbereflectedin theresultsofbinauralpitchmatches,
i.e.,MA wouldbe
971
LEVEL
OF NOISE
(dB SPL)
expected
to matchthe pitchof all toneswith frequencies
below500 Hz in her impairedear to approximately500 Hz
in her normal ear.
The otherfivesubjects
in the experiment,two of whom
showPTC's which suggestan abnormalplaceof cochlear
response,
all havebinauralimpairments.
Thustherewould
beno obviouspredictions
for binauralpitchmatches.However,Ward {1954}hasshownthat,for subjects
with musical
training,octaveadjustments
can givean indicationof frequencies
at whichpitch-frequency
irregularities
occur.For
the subjects
in thisexperiment,
onewouldpredictdichotomous results for "octave above" matches between the sub-
250 and 500 Hz.
IV. EXPERIMENT
1
Quiet
J. Acoust. Soc. Am., Vol. 73, No. 3, March 1983
jectswithnormallytunedPTC'sandthosewithabnormally
tuned PTC's. The subjectswith normally tuned PTC's
wouldbe expectedto adjustthe octaveto a frequencyap-
proximately
a physical
octaveabovethestandard
frequency,
asdonormal-hearing
subjects.
Themusically
trainedsubject
with abnormallytuned PTC's {KB}, on the other hand,
wouldbe expectedto matchthe octaveof low-frequency
tonesto approximately
an octaveabovethe MMF of her
PTC's,in otherwords,to a frequencyof approximately
2000
Hz.
A. Methods
1. Binauralpitch matches
Pitchmatchesbetweenthe impairedandnormalcarof
theunilaterallow-frequency
hearinglosslistener(MA} were
obtainedat 250 and 500 Hz. All toneswerelow-passfiltered
beforepresentation
to thesubject;
second-harmonic
distortioncomponents
{measured
electrically}
weremorethan65
dB below the fundamental and the remaining components
were more than 75 dB below. Temporally sequentialtone
pairswerepresented
to the listener,whoadjusted
the frequency
of thesecond
or variable
toneto matchthepitchof
the first,or fixedtone.The fixed-frequencytonewaspresentedto the abnormalear,whilethe variabletonewaspresented
to the normal ear.
Both the fixed-and variable-frequency
toneswere 500
msin durationwith 25-msrise-decaytimes.Silentintervals
of 500 ms separated
the fixedand variabletones.This seTurner eta/.' Pitchand low-frequencyhearingloss
971
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quence
oftonepairswasrepeated
every
2.25suntilthelistener indicated that a satisfactorypitch match had been
made. Beforethe next presentation,the frequencyof the
variabletone wasrandomlysetby the experimenterwithin
plusor minus25% of thefixed-tone
frequency
to preventthe
listenerfrom usingthe adjustmentknobasa referencefor the
nextjudgment.
Therangeoffrequencies
available
tothesubject at any time was at least400 Hz, and if the subjectrequested,this entirerangecouldbe increased,shiftedup, or
shifteddownby the experimenter.The listenerwasinstructedto makeequalpitchjudgmentsby settingthevariabletone
to both a "higher" and a "lower" pitch than the standard,
andthenapproachthepointof pitchequality.The intensities
of the two toneswereequal,setto the lowestlevelat which
the fixedtonegaveriseto a pitch sensationin the impaired
ear with which the listener felt she could make consistent
matcheswith the normal ear. At least 14 judgmentswere
obtainedat eachfrequency;the meanandstandarddeviation
at that frequencywere calculatedfrom the final ten judgments.
2. Octavejudgments
Four listeners,all with previousmusicaltraining,performed octavejudgments.Three listenershad normally
tuned PTC's {CA, CX, DR); the fourth listener{KB) had
abnormallytuned PTC's. The stimuli and test equipment
werethe sameasin thebinauralpitch-matchingexperiment,
exceptthatbothtoneswerepresented
to thesameearandthe
subjects'task was to adjustthe variablefrequencytone to a
pointwhichwas 1 octabovethe pitchof thefixedfrequency
tone. Both toneswere set to the same intensitylevel; this
level was the lowestthat the individual subjectfelt comfortablewith for musicalintervaljudgments.Priorto eachjudgment, the frequencyof the variabletone wassetby the experimenterto a randomvaluewithin plusor minus25% of
the physicaloctavefrequency{twicethe frequencyof the
fixedor lower-frequency
tone).For the firsttwo adjustments
from eachlistener,however,the two toneswere setinitially
to the samefrequency,and the listenerincreasedthe frequencyof the variabletoneto the subjectiveoctaveinterval.
In all casesthe first two judgmentswerewithin 25% of the
physicaloctave.If the subjectrequested,presentation
of either of the tonescouldbeomittedfor a periodof time,or the
rangeof frequenciesavailablefor the variabletonecouldbe
shiftedup or down.At least12judgmentsweremadeat each
of the frequencies
of the fixedtone{250and 500 Hz) and the
TABLE I. Binauralpitch matchesfor listenerMA.
,
•
,
Mean
Frequency
LE {fixed)
Level
{dBSPL)
frequency
RE {adjust}
Standard
deviation
250 Hz
75
263.5 Hz
13.5
500 Hz
70
513.0 Hz
17.5
of the abnormallytuned PTC at 250 Hz. Although the
matchingvariabilityissignificantly
higherthanthat typically shownby normal listenersat thesefrequencies,it is an
order of magnitudesmallerthan the predictedpitch shift.
Increasedvariability in pitch matchingtasks,and larger
than normal frequencyDL's, are a consistentfinding in
heating-impairedlisteners{e.g., Gaeth and Norris, 1965;
Burns and Williamson, 1981; Zurek and Formby, 1981;
Turner and Nelson,1982).In addition,largeimprovements
in performancewith training have been noted in similar
taskswith heating-impaired
listeners{Gengel,1969;Turner
andNelson,1982).Due to the smallnumberof practiceadjustmentsallowedin this experiment,it is doubtfulthat the
presentstandarddeviationsrepresenta listener'soptimum
performance.
The resultsof octaveadjustmentsat 250 and 500 Hz by
the four listenerswith musicaltrainingare presented
in Table II. Only the octavejudgmentsof listenersDR at 500 Hz
and CX at 250 and 500 Hz were significantlydifferentfrom
the physicaloctave{t test,p < 0.05). Lookingat the mean
valuesof listeners'judgments,only listenerCX's octaveat
250 Hz would appearto be abnormal,in view of the small
"octavestretch"commonlyseenin normal-hearinglisteners
{Ward, 1954}.Thus the abnormallytuned PTC's of listener
KB, from which place theory would predict octavejudgmentsnear 2000 Hz, had no predictivevalue for listeners'
abnormaloctavejudgments.
The comparisons
betweenPTC's and the pitchjudgmentsindicatethat theplaceof theresponse
suggested
by the
PTC, has little or no correspondence
with binauralpitch
matchesor octavejudgments.Only minor shiftsor deviationsof pitch are associated
with largePTC differences,
and
in thosecases,the deviationsappearto be indistinguishable
from thoseobservedin listenerswith normallytunedPTC's.
TABLE II. Octaveadjustments.
final results were taken as the mean and standard deviation
of the final tenjudgments.
Frequencyof
fixed(lower) Level
B. Results
Table I summarizesthe resultsof the binaural pitch
matches at 250 and 500 Hz for listener MA.
It can be seen
that within the limits of matchingvariability,and the limits
ofnormaldiplacusis,
MA matches.a
toneofgivenfrequency
in her impairedear with a toneof identicalfrequencyin her
normalear. In particular,thereis no indicationof the interauralpitchdisparityof approximatelyan octavefor the 250Hz'matches,
aswouldbepredictedfromplacetheoryin light
972
J. Acoust.Soc. Am., Vol. 73, No. 3, March 1983
Listener
tone
(dBSPL)
Mean of
Standard
adjustments deviation
CA
250 Hz
500 Hz
85
80
1004.3 Hz
20.4
9.7
CX
250 Hz
500 Hz
75
75
584.8 Hz
1013.6 Hz
35.3
4.3
DR
250 Hz
85
503.1 Hz
9.9
500 Hz
80
1016.6 Hz
7.3
250 Hz
500 Hz
85
523.4 Hz
85
978.5 Hz
34.9
52.9
KB
501.9 Hz
Turner eta/.' Pitchand low-frequencyhearingloss
972
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V. EXPERIMENT
4
I
For listenerMA (experiment3),binauralpitch matches
at 250 Hz were performedat the sameintensitylevel as the
probetone usedfor the 250-Hz PTC, indicatingthat pitch
sensations
did not correspor•d
to the placeof responseindicated at that intensity level. The resultsof experiment 2,
however,suggestedthat the place of responseto low-frequencytoneschangedfor listenerKB as the sensationlevel
of the tone was increased. The 250-Hz
forward-masked
PTC
from listenerKB was measuredfor a probelevel of 75-dB
SPL, while octavejudgmentswere obtainedfor 85-dB SPL
tones.While the 250-Hz PTC at 75-dB SPL is clearly abnormally tuned, the possibilityexiststhat at 85-dB SPL the
placeof responsefor KB hasreturnedto normal. Pitch sensation,if encodedby the placeof response,would be expected to follow this changingplaceof response.A pitch sensation in KB at 250 Hz which corresponded to this
considerablechangein place of cochlearresponseshould
shiftnearly2 oct from highto low asintensityof the tonewas
increased.Pitch-intensityfunctionsfrom listenerKB, listener JN, and a normally tuned listenerwere measuredto explore this issue.
A. Methods
Pitch-intensityfunctionswere obtainedat 250 and 500
Hz usingthe methodof adjustment.Three listenersparticipatedin the experiment.The equipmentand stimuliwerethe
sameasin the binauralpitch-matchingexperiment,with the
exceptionthat both membersof the tonepair werepresented
to a singleear. The listeners'task was the same as in the
binauralmatches,that is, to adjustthe frequencyof the second or variable-frequency
tone until the pitchesof the two
toneswere equal.
The variable-frequency
tonewassetat an intensitylevel
approximatelymidway betweenthe subject'sthresholdand
100-dB SPL. Points on the pitch-intensityfunctionswere
generallygatheredat 5-dB incrementsof the fixed tone's
intensity,rangingfrom the lowestintensityat which the subject coulddiscerna pitch sensationup to an intensity30 dB
greateror about 100-dB SPL. At least 12 judgmentswere
made by the listener at each intensity combination and the
mean and standard
deviation
were taken from the last 10
judgments.The first set of judgments was made for I v
i
i
i
i
I
12 -
280
I0
--
'
275
8
-
6
- 265
• 4
- 260
,.
- 255 -r.
2
>.o
'
!
I
I
'
z
--
-2
-
0
-
I&l
245
n.
_
•-4 -
240
-6 -8
235
-
' -
- I0 -
230
..
225
KB (RE)
- 12 -
22.0
I
4n
I
•n
I
c.n
I
Din
?n
I
"'•
I
100
dB SPL
FIG. 6. Pitch-intensityfunctionat 250 Hz for listenerKB. Mean valuesof
frequencyadjustments
areplottedasa functionof theintensityof the fixed-
frequency
tone(I/). Theintensity
ofthevariable-frequency
tone(Iv)was80dB SPL. Vertical barsindicatethe standarddeviationsof the adjustments.
ferentfrom that of listenerJN (abnormallytunedPTC) or
listenerCX (normallytunedPTC).
Similar results were obtained for each of the listeners at
500 Hz in that the magnitudeof KB's pitch-intensityshift
wasnot substantiallylarger that that of the other two listeni
i
i
i
i
I
i
.
_
_
_
_
280
275
270
265
_.
_
•4
_
_
-- I/(Iv -- intensityof thevariable-frequency
tone,I/-
270
__
..
in-
260
255 •
..
tensityof the fixed-frequencytone).Subsequent
judgments
z
weremadeat largerintensitydifferences,
withIœaboveand
o
belowIv.
_
245 "'
.
240
..
B. Results
Figures6, 7, and 8 displaythe pitch-intensityfunctions
at 250 Hz for listenersKB, JN, and CX. The magnitudeof
the pitch-intensityshift (in terms of percent frequency
change)is on the order of 5% to 10% for all three listeners.
Although the standarddeviationsof listener KB's judgmentswere quite large, it is evidentthat this listener,who
wassuspected
of havinga 2-octplacechangeasa functionof
intensity,doesnot exhibit a corresponding
pitch shift. The
magnitudeof KB's pitch-intensityshift is not distinctlydif973
J. Acoust.$oc. Am., Vol. 73, No. 3, March 1983
235
-6
-8
.
_
230
225
-10
JN (RE)
-12
--
.
•
I
I
40
50
60
I
70
dB •
I
I
I
80
90
I00
220
FIG. 7. Pitchintensity
functionat 250Hz forlistener
JN.I v = 85-dBSPL.
Turnereta/.' Pitchand low-frequencyhearingloss
973
Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 134.84.192.102 On: Thu, 26 Dec 2013 20:39:47
12-
28O
I0-
275
8
-
6-
•4
.
-
270
-
265
-
260
- 255 •'
-
I
- 245•
-
240
h-- 4
-6
2•35
-8
230
225
-I0
cx (RE)
220
-12
I
I
i
50
60
i
i
i
i
70
80
90
I00
dBSPL
FIG. 8. Pitch-intensityfunctionat 250 Hz for listenerCX. Io = 75-dBSPL.
ers.Theseresultsimply that largechangesin the placeof
response
whichmayaccompany
intensitychanges
in some
listenersdo not correspond
to largeor consistent
changes
of
pitch.
va. DISCUSSION
The resultsof theexperiments
described
hereinindicate
that ratherlargechanges
of the spatialresponse
patterncorrespondto onlysmallchanges
of the pitchsensation.
These
findingssuggestthat the spatialresponse
patterndoesnot
play a largeor consistent
role in pitch perceptionat low
frequencies.Extremelyabnormalplacesof responsefor
somelistenersresultedin judgmentsof pitch which were
similarto thosefrom the listenerswith normalplacesof response.Widelydifferingplacesof response
acrosslisteners'
ears{includingthe two earsof the unilaterallyimpairedlistenerMA} did not leadto correspondingly
largedifferences
in pitchjudgments.In addition,in eachof thelisteners
with
abnormallytunedPTC's, theyappearedto havean identical
placeof response
for tonesof 250or 500Hz, yetthelisteners'
pitchjudgmentsreflecteddifferentpitch sensations
for the
two frequencies.
A theoryof pitch whichrelatesthe pitch
sensation
of eachlow-frequency
toneto a particularplaceof
response
alongthebasilarmembraneisclearlyinadequate
to
explaintheseresults.
•
A "timing" or temporal theory of pitch providesa
mechanismwhich would better explainthe binauralpitch
matchesand octaveadjustments
of the listenerswith abnormally tuned PTC's. Such a theory would predict similar
pitchjudgmentsfor a giventone in listenerswith widely
differingplacesof response,
andwouldalsopredictsubstantial differences
in pitchjudgmentsfor tonesat differentfrequencies,
evenif the tonesproducedidenticalplacesof re974
J. Acoust. Soc. Am., Vol. 73, No. 3, March 1983
sponsewithin the cochlea. The possibility exists that
listenersnormallyutilize placeinformationfor the codingof
pitch, but when deprivedof reliableplaceinformationas a
resultof ½ochlear
pathology,insteadutilize timinginformation to make pitchlikejudgments.However,it is difficultto
imaginehow and at what point the auditorysystemwould
decidethat the placeinformationwasunreliableand abandon it in favor of contradictorytiming information.
The large variabilitiesin frequencyadjustmentsdisplayedby somelistenersin theseexperiments(e.g., KB in
TableII and Fig. 6, CX in Table II} may havebeenthe result
of insufficient
practicesessions.
Alternatively,thelargesizes
of the standarddeviationscould alsobe relatedto the large
auditorybandwidthsimpliedby theselisteners'PTC's (Festen et al., 1977}.In supportof this conceptis the sharper
tuningdisplayedby JN (Fig. 3}andcorrespondingly
smaller
standarddeviationsin Fig. 7. Perhaps narrow auditory
bandwidthscorresponding
to the placeof maximumstimulation are necessaryfor the preciseextractionof temporal
information.This issuerequiresfurther researchwith well
practicedlisteners.
The conceptthat the placeof stimulationis not critical
for the codingof pitch of low-frequencytonescan be supportedby physiological
data. Neuronsof high CF can also
encodetemporalinformationfrom low-frequencystimuli
whenthe stimuliarepresentedat highenoughlevels(Kiang
and Moxon, 1974}.Resultsfrom patientsutilizinga single
channelof a ½ochlear
implant (Eddingtonet al., 1978}and
from experiments
with bandpass-filtered
AM noisestimuli
(Burnsand Viemeister,1981}confirmthe resultthat differentfrequencies
of temporalstimulationcanencodedifferent
pitchlikesensations
from a singleplacein thecochlea.However,it is likely that the presentsingle-channel
½ochlear
implantsare onlyprovidinga grossapproximationof the temporal patterns available to normal listeners,since the
relationof the phaseof neuralfiringsto ½ochlearplacefor
low-frequency
stimuliappearsto be a complicatedfunction
(Ruggeroand Rich, 1982}.
In orderfor any temporaltheoryof pitchperceptionto
providea satisfactory
explanationof thepresentresults,and
of the resultsof previousresearchers
(e.g.,Eganand Meyer,
1950;Ward, 1964;Verschuureand Van Meeteren, 1975},it
is necessary
to accountfor the smallpitch-frequency
irregularitieswhich are observedin somelisteners.If the auditory
systemdetermines
pitchfromtheneuraltiminginformation,
the theoristmustsearchfor evidenceof somesort of irregularity in the physiologicalsynchrony-of-neural-firings
data.
There are somedata from measurements
of activity in single
unitsof the auditory nervewhich suggestthat suchirregularitiesmay exist (Ogushi,1978}.It is also likely that the
temporalinformationwould be extractedfrom neural responses
at a levelof theauditorysystemlocatedmorecentral
than the auditorynerve.If the ½ochlearresponsepatternor
placeof maximumresponse
is merelyresponsible
for directingtheauditorysystemto sampletiminginformationfroma
particularplaceon the cochlea,thensmalldeviationsin the
timinginformationwhichmay existbetweendifferent½ochlear placesmay be revealedas the responsepattern is
changed.In thismanner,ratherlargechangesin the spatial
Turner eta/.' Pitchand low-frequencyhearingloss
974
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response
patternwouldbereflected
in onlysmallchanges
in
pitch.
ACKNOWLEDGMENTS
•
This researchwassupportedby grantsfrom NINCDS
{NS 12125,NS 15451,andNS 15405}.This publication
is
baseduponresearch
performed
by C. Turneraspartialfulfillmentof the requirements
for the doctoraldegreeat the
Universityof Minnesotaundertheadvisorship
of W. Dixon
Ward. Portionsof this paperwere presentedat the 103rd
Meetingof the AcousticalSocietyof America,Chicago,
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