Delivering Different Signals to the Two Ears to Assess the Integration Or
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DOCUMENT RESUME ED 026 788 48 EC 003 479 By-Semmel, Melvyn I.; And Others The Brain As a Mixer, I. Preliminary LiteratureReview: Auditory Integration. Studies in Languageand Language Behavior, Progress ReportNumber VII. Michigan Univ., Ann Arbor. Center for Research onLanguago and Language Behavior. Spons Agency-Office of Education (DHEW),Washington, D.C. Bureau of Research. Bureau No-BR-6-1784 Pub Date 1 Sep 68 Contract-OEC-3-6-061784-0508 Note-11p. EDRS Price MF -$0.25 HC-$0.65 Descriptors-*Audition (Physiology), AuditoryDiscrimination, Auditory Perception, AuditoryTests, *Aurally Learning Handicapped,AuralStimuli,ClinicalDiagnosis,*ExceptionalChildResearch,*Identification, Disabilities, Minimally Brain Injured, *NeurologicalDefects, Neurologically Handicapped, Neurology,Perception, Research Reviews (Publications), SensoryIntegration Methods to evaluate central hearingdeficiencies and to localize braindamage are reviewedbeginning with Bocca who showedthat patients with temporallobe tumors made significantlylower discrimination scores in the earopposite the tumor when speech signals were distorted.Tests were devised to attempt to pinpointbrain damage on the basis of auditory tests;Jerger found that both temporallobe tumors and brain-stem damage couldlead to the same results on the tests.Bocca suggested delivering different signals to the two earsto assess the integration orbinaural summationofthecentralneuralsystem.Matzker suggested twoindividually meaningless sounds presentedsimultaneously, one to each ear; a normalsystem would apparently integrate soundsbetter. Studies by Bocca, Jerger,Sanchez-Longo, Forster, Matzker, Harris, and Hayashiindicated that subjects with organic symptoms showed poorer integration thansubjects without these symptoms;however, it was not clear where binauralintegrationtook place.Conclusions were thatMatzker's procedure is probably inadequate as ageneral test to localize braindamage. More research is indicated as the techniqueshows promise for studying anorganism's binaural integration abilities.(RP) -/711/ U.S. DEPARTMENT OF HEALTH,EDUCATION & WELFARE OFFICE OF EDUCATION ?Az Ve' RECEIVED FROM NE THIS DOCUMENT HAS BEENREPRODUCED EXACTLY AS POINTS OF VIEW OR OPINIONS PERSON OR ORGANIZATIONORIGINATING IT. REPRESENT OFFICIAL OffICE OFEDUCATION STATED DO NOT NECESSARILY POSITION OR POLICY. THE BRAIN AS A MIXER,I. PRELIMINARY LITERATUREREVIEW: AUDITORYINTEGRATION1 Melvyn I. Semmel, DaleLewellyn., Gillian lowes, andJudith Agard Center for Research onLanguage-and Language Behavior The UniversitTof Michigan In a review of earlierwork on techniques forstudying central procedure auditory integration,Matzker's (1958) binaural.fusion emerges as the mostpromising method for-measuringbinaural inte- gration abilities. central hearing Progress has been slowin-developing-methods to.evaluate often.judged by the otologist deficiencies. Patients with.central-lesions-are The-reason-is.the bilateral cerebral cor- to haveessentially.normal-hearing each.ear projects to tical representation ofhearirs foreach earl -bedause must-be-enormous-and pro- both sides of the brain, alesion within-the'brain before it bably lethal (coveringauditory.areas%on-both-sides.of-the brain) More sensi- results in deafnessmeasurable.by.a conventional hearing test. tive tests of-auditorydiscriminationoften-involve-the-patienes intelligence, results that education, and memory, aswell as his-hearing.,-and-so.produce are difficult tointerpret. in the early 1950's One of the firstbreak-throughs on.this.problem came understand when Bocca (1955) and hiscolleagues.showed that-the-ability to contralateral ear of pa.7 distorted speech wasmodified.substantially-in the tients with temporallobe'tumorw. .Thepatients-had.essentially-normal'hearing but-when-the-speech signal for pure tones andundistorted.,.ordinary.speech, was distorted bylow-pass filtering,....acceieration-ofrate, periodic-interrup-.. the.discrimination scores weresigni.T. tion, or artificiallyscanning speech', lobe. ficantly lower for theear-opposite..the'side'of-the-pathological-temporal auditory Bocca's findingsuggested.w.new..use-for-two-standard-tests of (RH) and discrimination which were inwide.use%at-the-timey.The Rush-Hughes phoneticallybalanced (PB) monosyllabic W22 tests bothinvolved-delivering-50 366 Semmel, Lewellyn, Lowes & Agard 2 words and asking the subject to repeat each word. Indiv±eually, the tests were ineffective in diagnosing brain damage, but it turned out that in combination they could. Investigators had noticed that the RH"test consistently resulted in 20% more errors than the W22, apparently as aresult of distortion in the RH re- cordings and of the clipped and speedier method of presenting the words.A difference in score greater than 20% between the two tests was found to indi- cate a disturbance in the auditory areas ofthe temporal lobes; and it was particularly in the ear contralateral to the damaged hemisphere that such a difference would appear (Goetzinger, Dirks, & Baer,1960). Apparently the greater difficulty of the RH test functions inthe same manner as the distor- tions of speech in Bocca's work. Jerger (1954) provided further-evidence from 24 patientswith organic CNS disease. He used five monaural tests, three of them simple testsof the type developed by Bocca and his colleagues. The UL or "undistorted loud" test required subjects to repeat 50 PB words which were presented50 db above threshold. The UF or "undistorted faint" test delivered50 PB words at only 30 db above threshold. The LPFS, or "low-pass filtered speech" test,delivered 50 PB words with a 500 cps filter, so that the words weremuffled and diffi- cult to understand. The two other tests differed.from the others-inthat they involved a primary signal to which the listener-had to attend inthe presence of a sec- ondary or competing signal on the non-test ear. Test #2 presented 50 PB words (50 db above threshold) to one ear; while.adifferent speaker simultaneously read a complete sentence to the other ear at alevel 10 db more intense than the PB words. The subject had to ignore the sentences in one ear and repeat aloud the PB words he heard in the-other. Test #3 was similar to test #2 except that the test signal was acomplete sentence requiring a multiple- choice answer, and the competing signal on theother ear was the continuous discourse of two different speakers-. Scores for all of these tests were determinedseparately for the two ears, the ear homolateral and the ear contralateral tothe affected side of the brain. 367 v1,,,ext Semmel, Lewellyn, Lowes & Agard Jerger presentedresults..for%fourgroups of subjects. Group A consisted nucleus) of sevenpatients with low,brain-stemlesiond (below.the cochlear presumably not involving theauditory system....These patients, asexpected, showed normal testresultswitir.no%difference.between the.two ears on anyof the five tests. Group B consisted._of-sevenpatients with unilateral brainr stem damage involving theauditory.system. The.tests showed a 20% decrease The in number of correctresponses.for..the ear'contralateral tothe damage. only exception was in test#3,.where...performance was good on both ears. Group C consistedof.six%patients..with.unilateral temporal.lobelesions involving Herschl's gyrus.....The'.results'were..quitesimilar to those.for.Group B, except that intests.#2.and..#3%the%contralateral'ear showed-a much poorer. Group C., four.subjects with response...In Group Dr designetLaw.a%control.for A.slight parietal, frontal., orremote..temporal..cortical.lesions.were.tested. that (5-10%) difference.between..the%two...earw.wasfound. .The.authors suggested the neurosur- the auditory system hadsustainett.somesecondary.damage during subjected. gical procedures towhich..all...the..patients..of-this..group.had been' brain-stem In summary, the PBmonaural...tests._apparently.detected. auditory however, or corticallesions. The..only..test..differentiating-between.locations, the was test #3. The.authors concludeththavit. was.too soom.to-comment on tested diagnostic value ofany.of..these._tests:%-...Many'more.subjects..had to.be the tests sup- and the location of the.central.iesions'checked... To.be sure, in the ported Bocca's findingsof.decreased...ability.tounderstand some-signals they also. contralateral ear ofpatients..with..temporal'lobe tumors;.however, What was needed showed that brain-stem.damage..couitl%lead.to.the'same result. .Again it was Bocca (1961) was a test thatcouldlocaliie.the..area..of.damage-. involved simul- who suggested the method'to..aid'Aru.solving-this-problem.. -It taneously'delivering different%signals%to.thetwo ears, and.studying'the syn- I thesis or.integrationoU.these..messages: . This.phenomenon. ofbilateral-Ausion.or-integration.has.an-interesting people history.' Throughoutthe.nineteenth-_and..early-twentieth.centuries-most thought that therewas..no..real%binaural...summation.of-intensity.or.loudness, butsimply.a.sensation'of..greater%ciarity..and.fullness-of..sound....However, that at the later studies..ofsummatiolv.at...threshoidgavesubstantial..evidence level:of the CNS.a.nearlyperfect.summationof'the'stimuli.heard'by.the two Semmel, Lewellyn, Lowes & Agard 4 ears does occur. An experiment by Bocca (1955) gave_clear.evidence of_this summation. He used both nonsensical_and meaningful disyllabic-words.,_First he presented to one ear a normal voice.deliveringthesewords and lowerecLthe intensity until the subject was.unable to identify. and repeat more then30% -of the words. Then to the other ear.he presented the same words