Braz. j. . vol.80 número4

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Brazilian

Journal

of

OTORHINOLARYNGOLOGY

www.bjorl.org

ORIGINAL

ARTICLE

Music

students:

conventional

hearing

thresholds

and

at

high

frequencies

夽

Débora

Lüders

a,∗

,

Cláudia

Giglio

de

Oliveira

Gonc

¸alves

a

,

Adriana

Bender

de

Moreira

Lacerda

a

_,

_Ângela

_Ribas

a

_,

_Juliana

_de

_Conto

b

a_Universidade_Tuiuti_do_Paraná,_Curitiba,_PR,_Brazil

b_Universidade_Estadual_do_Centro-Oeste_(UNICENTRO),_Guarapuava,_PR,_Brazil

Received11March2013;accepted30August2013 Availableonline6June2014

KEYWORDS

Music; Students; Hearing;

Hearingloss;

Audiometry

Abstract

Introduction:Researchhasshownthathearinglossinmusiciansmaycausedifficultyintimbre recognitionandtuningofinstruments.

Aim:Toanalyzethehearingthresholdsfrom250Hzto16,000Hzinagroupofmusicstudents andcompare them to anon-musician group inorder todetermine whetherhigh-frequency audiometryisausefultoolintheearlydetectionofhearingimpairment.

Methods:Study design was a retrospective observational cohort. Conventional and high-frequencyaudiometrywas performedin42 musicstudents(Madsen IteraII audiometerand TDH39Pheadphonesforconventionalaudiometry,andHDA200headphonesforhigh-frequency audiometry).

Results:Ofthe42students,38.1%werefemalestudentsand61.9%weremalestudents,witha meanageof26years.Atconventionalaudiometry,92.85%hadhearingthresholdswithinnormal limits;butevenwithinthenormallimits,theworstresultswereobservedintheleftearfor allfrequencies, exceptfor4000Hz;compared tothenon-musiciangroup,the worstresults occurredat500Hzintheleftear,andat250Hz,6000Hz,9000Hz,10,000Hz,and11,200Hzin boththeears.

Conclusion:Theperiodic evaluationofhigh-frequencythresholdsmaybeusefulintheearly detectionofhearinglossinmusicians.

夽

Pleasecitethisarticleas:LüdersD,Gonc¸alvesCG,LacerdaAB,RibasÂ,deContoJ.Musicstudents:conventionalhearingthresholds andathighfrequencies.BrazJOtorhinolaryngol.2014;80:296---304.

∗_{Corresponding}_author.

E-mail:debora.luders@yahoo.com.br(D.Lüders).

http://dx.doi.org/10.1016/j.bjorl.2014.05.010

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PALAVRAS-CHAVE

Música; Estudantes;

Audic¸ão;

Perdaauditiva;

Audiometria

Estudantesdemúsica:limiaresauditivosconvencionaiseemaltasfrequências

Resumo

Introduc¸ão: Pesquisascomprovamqueaperdaauditivaemmúsicospodegerardificuldadeno reconhecimentodetimbresenaafinac¸ãodosinstrumentos.

Objetivo: Analisaroslimiaresauditivosde250Hza16.000Hzdeum grupodeestudantesde músicaecompará-losaumgrupodenãomúsicosparadeterminarseaaudiometriadealtas frequênciaséumrecursoútilnadetecc¸ãoprecocedadeficiênciaauditiva.

Método: Formadeestudo:observacional,de coorte,retrospectivo. Realizou-se audiometria convencionaledealtasfrequênciasem42estudantesdemúsica(audiômetroMadsenIteraII, fonesTDH39PparaaaudiometriaconvencionaleHDA200paraaudiometriadealtas frequên-cias).

Resultados: Dos42estudantes,38,10%eramdogênerofemininoe61,9%dogêneromasculino, commédiade26anos;naaudiometriaconvencional92,85%apresentaramlimiaresauditivos dentrodospadrõesdenormalidade;mesmodentrodanormalidade,pioresresultadosocorreram naorelhaesquerdaparatodasasfrequências,excetuando-se4000Hz;quandocomparadoao grupodenãomúsicosospioresresultadosocorreramem500Hznaorelhaesquerdae250Hz, 6000Hz,9000Hz,10.000Hze11.200Hzemambasasorelhas.

Conclusão:Aavaliac¸ãodoslimiaresdealtasfrequênciasdeformaperiódicapodeserútilna detecc¸ãoprecocedadeficiênciaauditivaemmúsicos.

Introduction

Music hasalways been connected topeople’s life history,

as a marker of both good times and bad times, and has

increasinglybecomethefocusofattentionofprofessionals

in severalfields, mainlyexperts in hearingand acoustics.

Thisinterestisduetothefactthatexposuretomusicisnot

onlyasocialissue,butalsoaprofessionalissue.

However,whatisintendedtobeenjoyableand

stimulat-ingcandamagethehearing,consideringthatmusic,aswell

asnoiseat highintensities,cancauseirreversibledamage

tohearing.1

Inastudy2 _performed_in_music_schools _in_Germany,_the

sound intensity duringthe rehearsal of amajor orchestra witharomanticmusicrepertoireexceeded85dB(A).Ifthe musiciansworked foreighthoursaday, fivedaysaweek, noiseexposureformostwouldexceedtheuppertolerance threshold.

Anotherstudy,3 _performed_by _the_music _research

insti-tuteoftheUniversityofNorthCarolinaintheUnitedStates, foundthat52%ofthestudentswhoparticipatedina wood-wind instrument band, and who attended one or more rehearsals perweek, wereexposedtosoundlevelshigher than 100%of theallowed dose, according totheNational Institute for Occupational Safety and Health (NIOSH). At above100%ofthenoiselevelsasdefinedbyNIOSH,these students are exposed to very dangerous levels of sound intensity during a singlerehearsal. Atotal of 40 students (representing brasswind, woodwind,and voice)showed a meanlevelof87---95dB(A),withbrasswindshowing signifi-cantlyhigherlevels.

Among the many factors that make grouprehearsals a risktohearingarethedurationofexposure,theintensity ofmusic,theacousticsoftherehearsalspace,proximityto

noisesources(when theyarenot thesound sourceitself, as in the case of singers), choice of repertoire, and the repetition of specific musical passages. Mostly, it is the grouprehearsalthatpreparesstudentsfortheirprofessional careers.Therefore,theconductorsoftheserehearsals are important models for the students. Methods of hearing conservationinthistypeofactivityshouldbeincorporated andsharedbetweentheconductorsandstudentsasamatter ofprofessionallongevity.3

The literature has many studies4---10 _that _present

hear-inglossasaresultofexposuretomusicathighintensities, alsoaccompanied bysymptomssuchastinnitus,sensation ofearfullness,headache,anddizziness.Thesesymptoms, alongwithnon-auditory manifestationssuch asirritability andfatigue,maybethefirstsignsofhearingdamage.11

Thelossoftheexternalciliatedcells,causedbyconstant andsystematicexposuretohighsoundpressurelevels,can producea reductionin cochlear amplification(motility of theexternal ciliated cells), resultingin loss of sensitivity tolow tomoderatesounds (40---60dB HL).This causesthe musiciantoplayand/orsingatincreasinglyhighervolume, leadingtohigherphysical effortandgreater hearingloss. The loss of external ciliated cells also reduces frequency selectivityandspectralresolutionofthecochlea,leadingto diplacusis(abnormalperceptionofpitch).Thisconditioncan putthemusician’scareeratriskforthosewhooftenmake decisionsaboutthevocaland/orinstrumentaltone perfor-mance. In addition,damageto theexternal ciliated cells leadstolackofcochlearcompressionorrecruitment (abnor-malloudnessperception), which can shortena musician’s career.12

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formusicians,canhaveseriousconsequencesfortheir pro-fessionalperformance.13

Conventionalpure toneaudiometry(PTA)is considered thebasisof audiological evaluation,representingthefirst test that composes the assessment. It aimsto determine theindividual’sminimumthresholdofaudibilityfor frequen-ciesfrom250Hzto8000Hz.Thisevaluationtechniqueisthe mostwidelyusedfor thedetectionofhearinglossin indi-vidualsexposedtohighsoundpressurelevels,eithernoise ormusic,especiallyatintensities>85dB(A).14,15

Although hearing disorders can be detected by con-ventional PTA, currently, due to the emphasis on health promotion,professionalsandresearchershaveincreasingly sought to identify these alterations as early as possible. In relation to sensorineural hearing loss, high-frequency audiometryhasbeen usedasawaytodetect these alter-ationsatanearlystage,sothatpreventioncanbeperformed before more significant lesions occur, according to the conceptofhealthpromotion.16

In a literature review17 _on _the _contribution _of

high-frequency audiometry to the early identification of noise-inducedhearingloss,theauthorsconcludedthatthe hearing thresholds at high frequencies are often reduced earlierthanconventionalfrequencythresholds,from250Hz to8000Hz,andtherefore,theyshouldbeusedin occupa-tionalhearinglosspreventionprograms.

TheII InternationalCongressofMedicinefor Musicians, held in September 2005 in Spain, stressed that musicians areprofessionalswithahighriskofoccupationaldiseases, alsoemphasizingthatthereisalackofawarenessaboutthis risk,andlittledemandforinformationthatcanpreserveand managethe working conditions of this professional class. Although advances have occurred, preventive and health maintenanceactionsarestillfarfromtheideal.18

Inthefieldofmusic,musicstudentsandteachers, admin-istratorsofmusicschools,andconservatorieshavenotmade anefforttopreventseveralhealthrisksinvolved inmusic learningandperformance.19

Thus, it is imperative that preventive measures are taken,togetherwiththisprofessionalclass,tominimizethe harmfuleffectsofexposuretohighsoundpressurelevels; thisconcernhasledtothisstudy,whichaimedtoanalyze thehearingthresholdsof250---16,000Hzinagroupofmusic studentsandcomparethemtoacontrolgroup,todetermine whetherhigh-frequencyaudiometrycanbeausefultoolfor earlyidentificationofhearingimpairment.

Materials

and

methods

Thiswasanobservational,retrospectivecohortstudywitha quantitativeapproachthatanalyzedtheauditorythresholds of 250---16,000Hz in a group of undergraduate music stu-dents,comparedtoagroupofnon-musiciansandnon-music students.

This research had the approval of the research ethics committee, No. 190/2011, and all individuals assessed signed an informed consent, after receiving information about the objectives, rationale, and methodology of the proposedstudy.

The sample consisted of 84 subjects, divided into two groups:onegroup(G1)consistingof42undergraduatemusic

studentsandonegroup(G2)comprising42individualswho werenon-musiciansandnon-musicstudents,andwhowere notexposedtonoiseatwork.Studentswerefromthree pub-liceducationalinstitutionsdistributedacrossseveralareas of study (music education, popular music, instruments, music compositionandconducting,sound production,and singing)andallparticipatedinacademicpracticeactivities together.

Theinclusion criterionfor group G1comprised beinga music student, and theexclusion criteria included having conductiveand/orsensorineuralhearingdisordersnot asso-ciatedwithnoiseexposure,evaluatedbyaudiometric and imitanciometryassessment.

Initially,visualinspectionoftheexternalauditory mea-tuswasperformed withaKoleotoscopetoverifypossible obstructionsoftheexternalauditorycanalthatcouldimpair theaudiologicalassessment.Onlytwostudentshadexcess wax, which was removed by an otorhinolaryngologist at the clinic where audiological evaluations wereperformed beforethestartoftheexamination.

Theaudiologicalevaluationswereperformedwitha Mad-senaudiometer; modelITERAIIwithTDH39Pheadphones fortheconventionalaudiometry,andHDA200headphones for high-frequencyaudiometryandaudiometric booth.All individualswereassessedaccordingtothecurrentstandards (CFFa,2010).Theauditoryrestbeforetheaudiological eval-uationwas14h.

The conventional PTA assessed air-conduction hearing thresholdsatfrequenciesfrom250Hzto8000Hzandbone conduction hearing thresholds, when the air conduction thresholds showed values >25dB HL for frequencies from 500Hzto4000Hz.

The high-frequency tone audiometry assessed air-conduction hearing thresholds at frequencies of 9000Hz, 10,000Hz,11,200Hz,12,500Hz,14,000Hz,and16,000Hz.

Student’st-testwithasignificancelevelof0.05(5%)was usedforthestatisticalanalysis.

Results

InG1,age rangedfrom18 to58years,witha meanof 26 years,medianof25.7years,andstandarddeviationof7.7 years.Regardinggender,38%werefemalestudentsand62% were male students. The time of musical practicevaried between one and 41 years, witha mean of 11.17 years, medianof10years,andstandarddeviationof8.42years.

Among the 42 students, 69% played string instruments (mainlytheguitar),16.66%playedwoodwindandbrasswind instruments, 16.66%playedthe piano,14.28% played per-cussion,and4.76%sang.Severalstudentsplayedmorethan onemusical instrumentor sangand alsoplayedan instru-ment.Atotalof80%haveplayedand/orsungformorethan fouryears,and56%havebeenamemberofamusicalgroup formorethanfouryears.Allstudents(100%)participatedin academicpracticeactivitiestogether.

InG2,agerangedfrom18to56years,withamean25.8 years,medianof24.5years,andstandarddeviationof7.5 years.Regardinggender,38%werefemalestudentsand62% weremalestudents.

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Table1 Meanconventionalandhighfrequencypure-toneair-conductionhearingthresholdsinG1andG2(n=84).

Ear Frequency(Hz) G1(n=42) G2(n=42) p

MeandBHL Standarddeviation MeandBHL Standarddeviation

Right 250 10.1 4.6 8.0 4.0 0.0255a

500 8.5 3.2 6.8 5.0 0.0745

1000 5.5 4.9 5.2 4.4 0.8158

2000 3.9 4.6 5.4 5.0 0.1772

3000 3.2 5.8 6.0 5.7 0.0317a

4000 6.2 7.1 8.0 6.8 0.2414

6000 9.6 8.8 9.0 7.0 0.7324

8000 7.4 7.8 8.2 6.7 0.6016

9000 12.6 10.9 7.9 8.5 0.0286a

10,000 13.3 11.2 11.8 9.8 0.5021

11,200 13.1 11.0 9.9 9.3 0.1535

12,500 8.3 11.2 14.9 10.3 0.0066a

14,000 3.5 14.2 15.5 12.8 0.0001a

16,000 7.0 17.5 17.0 16.5 0.0085a

Left 250 10.7 5.1 7.6 4.5 0.0041a

500 9.9 3.6 7.0 5.1 0.0037a

1000 5.4 5.7 6.2 5.7 0.5044

2000 6.4 7.4 6.2 5.2 0.8650

3000 4.6 8.9 6.0 5.7 0.4219

4000 5.7 9.5 7.7 6.6 0.2624

6000 10.2 13.3 8.8 7.9 0.5527

8000 7.5 12.6 8.0 6.4 0.8280

9000 12.7 13.6 8.9 8.6 0.1292

10,000 13.8 14.7 10.7 8.2 0.2369

11,200 13.5 15.0 10.8 9.9 0.3473

12,500 9.2 15.3 16.5 12.0 0.0162a

14,000 5.7 16.9 15.4 13.9 0.0055a

16,000 7.6 20.6 15.9 13.7 0.0353a

a _Student’s_t_-test_with_significance_level_of_0.05.

Table2 Meanconventionalandhighfrequencypure-toneair-conductionhearingthresholdsofrightandleftears,perfrequency, inG1(n=42).

Frequency(Hz) Rightear Leftear p

250 10.1 4.6 10.7 5.1 0.3420

500 8.5 3.2 9.9 3.6 0.0125a

1000 5.5 4.9 5.4 5.7 0.8642

2000 3.9 6.4 4.6 7.4 0.0109a

3000 3.2 5.8 4.6 8.9 0.1477

4000 6.2 7.1 5.7 9.5 0.6818

6000 9.6 8.8 10.2. 13.3 0.7289

8000 7.4 7.8 7.5 12.6 0.9336

9000 12.6 11.9 12.7 13.6 0.9371

10,000 13.3 11.2 13.8 14.7 0.7789

11,200 13.1 11 13.4 15 0.8303

12,500 8.3 11.2 9.2 15.3 0.6238

14,000 3.4 14.2 5.7 16.9 0.0814

16,000 7 17.5 7.6 20.6 0.7249

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Table3 Meanpure-tone air-conductionhearingthresholdsofrightandleftears,perfrequency,betweenmaleandfemale genders(n=42).

Frequency(Hz) Male(n=26) Female(n=16) p

RE LE RE LE RE LE RE LE RE LE

250 9.4 12.2 4.5 5.8 11.3 9.8 4.7 4.6 0.2172 0.1463

500 8.5 10.0 3.1 3.7 8.4 9.8 3.5 3.6 0.9816 0.8680

1000 5.6 4.7 3.8 6.7 5.3 5.8 6.4 5.0 0.8680 0.5550

2000 4.2 6.3 4.4 9.6 3.4 6.5 5.1 6.0 0.5955 0.9045

3000 2.7 5.0 5.9 11.1 4.1 4.4 5.8 7.4 0.4659 0.8406

4000 5.6 8.7 7.5 12.2 7.2 3.8 6.3 7.1 0.4793 0.1063

6000 10.4 12.8 9.6 19.9 8.4 8.7 7.5 6.9 0.4926 0.3327

8000 7.5 9.7 7.4 17.6 7.2 6.2 8.8 8.4 0.9018 0.3841

9000 12.5 14.1 12.0 15.3 12.8 11.9 9.3 12.7 0.9297 0.6271

10,000 13.1 13.8 12.2 18.6 13.8 13.8 9.7 12.1 0.8526 0.9839 11,200 14.6 15.3 12.3 18.7 10.6 12.3 8.3 12.4 0.2604 0.5350

12,500 8.3 11.3 11.7 20.8 8.4 7.9 10.6 11.1 0.9629 0.4966

14,000 2.7 8.4 12.3 22.2 4.7 4.0 17.2 12.8 0.6631 0.4188

16,000 2.1 13.1 11.8 25.2 15.0 4.2 22.2 16.8 0.0183a _0.1768 RE,rightear;LE,leftear.

a_Student’s_t_-test_with_significance_level_of_0.05.

audiometry:a20-year-oldstudent(hearinglossat 6000Hz intherightear),whohadplayedtheguitarforthreeyears;a 34-year-oldstudent(hearinglossat8000Hzintheleftear), whohadplayedthetrombonefor20years,anda 36-year-oldstudentwithbilateralalteration(6000Hzintherightear and2000---8000Hzintheleftear),whohadplayedtheguitar foroneyear.Inallthreecases,therearenoreportsofthe useofhearingprotectiondevices.

Table 1 compares the thresholds of conventional and high-frequencyaudiometrybetweenG1andG2.

Itwasobserved thattherewasa significant difference betweenG1andG2atcertainfrequencies;inG1themean thresholdswereworsethanG2atthefrequency of250Hz

inbothears,andat500Hzintheleftear.Thestudygroup hadbettermeanthresholdsonlyat3000Hzintherightear, whencomparedtothecontrolgroup.

Inrelationtohigherfrequencies,therewasasignificant differencebetweenG1andG2at12,500Hz,14,000Hz,and 16,000Hzinbothears,andthemeanthresholdswere bet-ter in the study group than the control group. Only the mean thresholdof the 9000Hz frequency in the right ear wasworseinthestudygroupwhencomparedtothecontrol group.

Table 2 compares the thresholds of conventional pure toneandhigh-frequencyaudiometryofG1intherightand leftears.

Table4 Meanrightearhearingthresholds,perfrequency,forageupto25years(n=50).

Frequency(Hz) Upto25years---rightear p

G1(n=25) G2(n=25)

250 10.0 5.2 7.6 3.6 0.0951

500 9.0 3.5 8.2 5.0 0.0037a

1000 5.6 5.6 5.9 4.0 0.5743

2000 4.2 5.3 4.4 3.5 0.2142

3000 1.2 5.0 6.8 5.3 0.0096a

4000 4.2 5.9 9.4 7.0 0.0997

6000 9.4 8.7 11.2 7.6 0.4320

8000 6.2 7.0 9.4 7.7 0.4715

9000 10.2 8.1 11.2 10.5 0.0319a

10,000 9.6 8.0 16.5 11.7 0.6614

11,200 10.6 8.0 14.8 11.8 0.0740

12,500 5.0 7.6 19.1 12.5 0.0032a

14,000 −0.8 8.0 21.8 17.1 0.0000a

16,000 1.4 14.6 22.0 19.4 0.0019a

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Table5 Meanpure-toneair-conductionrightearthresholds,byfrequency,foragerange26andolder,ingroupsG1andG2 (n=34).

Frequency(Hz) Age26andolder---rightear p

G1(n=17) G2(n=17)

250 10.3 3.7 7.7 3.6 0.0239a

500 7.7 2.6 8.2 5.0 0.6082

1000 5.3 3.7 5.9 4.0 0.6959

2000 3.5 3.4 4.4 3.5 0.4836

3000 6.2 5.7 6.8 5.3 0.7825

4000 9.1 7.8 9.4 7.1 0.8975

6000 10.0 9.2 11.2 7.6 0.6989

8000 9.1 8.9 9.4 7.7 0.9290

9000 16.2 13.6 11.2 10.5 0.2489

10,000 18.8 13.1 16.5 11.7 0.6248

11,200 16.8 13.8 14.7 11.8 0.6793

12,500 13.2 13.8 19.1 12.5 0.2485

14,000 9.7 18.7 21.2 17.1 0.0773

16,000 15.3 18.4 22.1 19.5 0.2273

a _Student’s_t_-test_with_level_of_significance_of_0.05.

There was a significant difference between the mean thresholds in the right and left ears at frequencies of 500Hz and 2000Hz for the study group, with the left ear showing worse mean thresholds than the right ear.

Table 3comparesthe meanconventional andhigh fre-quency hearingthresholds of G1, takinginto account the frequency,gender,andear.

There was a significant difference between the mean thresholds of male andfemale genders only for the right

earat16,000Hz,withfemalestudentsshowingworsemeans thanthemalestudents.

Table4comparesthemeanconventionalpuretone air-conduction and high-frequency hearing thresholds in the right earbetween G1 and G2 for the age range up to25 years.

ThereisasignificantdifferenceforG1betweenthemean puretoneair-conductionhearingthresholdsinstudentsaged upto25yearsandG2at500,3000,9000,12,500,14,000and 16,000Hz,withthebestresultsreportedbyG1,exceptat

Table6 Meanpure-toneair-conductionthresholdsintheleftear,byfrequency,forageupto25yearsingroupsG1andG2 (n=50).

Frequency(Hz) Upto25years---leftear p

G1(n=25) G2(n=25)

250 10.0 4.8 8.2 4.3 0.0504a

500 9.4 3.6 5.8 4.9 0.0104a

1000 4.8 5.9 4.8 4.7 0.5025

2000 6.2 7.3 6.0 5.8 1.0000

3000 2.4 6.8 5.4 5.9 0.1081

4000 3.0 5.2 7.0 6.6 0.2228

6000 7.8 7.5 7.6 6.3 0.6252

8000 4.2 5.5 7.4 6.0 0.4570

9000 9.0 7.4 5.6 6.0 0.0875

10,000 10.8 8.0 8.6 6.8 0.3147

11,200 9.8 8.1 6.6 5.3 0.2563

12,500 6.0 9.0 12.0 7.5 0.0310a

14,000 2.2 10.7 11.6 6.9 0.0117a

16,000 3.6 17.8 13.6 13.5 0.3410

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Table7 Meanpure-toneair-conductionthresholdsintheleftear,byfrequency,foragerange26andolder,ingroupsG1and G2(n=34).

Frequency(Hz) Age26andolder---leftear p

G1(n=17) G2(n=17)

250 11.8 5.6 7.9 3.6 0.0143a

500 10.6 3.5 8.2 4.7 0.0564a

1000 6.2 5.5 6.5 5.2 0.8679

2000 6.8 7.9 6.2 5.2 0.7983

3000 7.9 10.6 7.4 6.6 0.8579

4000 9.7 12.8 9.1 6.4 0.8708

6000 13.8 18.7 11.8 9.2 0.6934

8000 12.4 17.9 12.1 6.6 0.9527

9000 18.2 18.5 13.8 9.6 0.4084

10,000 18.2 20.5 13.8 8.6 0.4440

11,200 18.8 20.7 15.9 11.9 0.6342

12,500 13.8 21.0 21.8 13.6 0.2267

14,000 10.9 22.6 10.9 14.8 0.1109

16,000 13.5 23.4 21.8 15.2 0.1748

a_Student’s_t_-test_with_level_of_significance_of_0.05.

thefrequencyof500Hz,wherebetterresultswereobserved inG2.

Table5 comparesconventionalpure-toneandhigh fre-quency air-conduction hearing thresholds in the left ear betweenG1andG2inthoseaged26yearsandolder.

TherewasasignificantdifferenceforG1betweenmean puretoneair-conductionhearingthresholdsinstudentsaged 26yearsandolderandG2onlyatthefrequencyof250Hz, withthebestresultsreportedbyG2.

Table6comparesthemeanconventionalpure-toneand highfrequencyair-conductionhearingthresholdsintheleft earbetweenG1andG2instudentsagedupto25years.

There wasa significant differencefor G1 between the mean pure tone air-conduction hearing thresholds in stu-dentsagedupto25yearsandG2atfrequenciesof250and 500Hz,whereG1hasworseresultswhencomparedtoG2.As forthefrequenciesof12,500and14,000Hz,thebestresults wereshownbyG1.

Finally, Table7comparesthe meanconventional pure-toneair-conductionandhighfrequencyhearingthresholds intheleftearbetweenthetwogroupsinstudentsaged26 yearsandolder.

There wasa significant differencefor G1 between the mean pure-tone air-conductionhearing thresholds in stu-dentsaged26yearsandolderand G2onlyat frequencies of250and500Hz,withthebestresultsreportedbyG2.

Discussion

Hearinglossinducedbyhighlevelsofsoundpressureoccurs bysystemicandprolongedexposuretoloudsounds(>85dB (A)/8h/day).Withaninsidiousonset,itsmainfeaturesare chronicityandirreversibility,asitaffectstheciliatedcellsof theorganofCorti.20---23_In_addition,_according_to_the_National

CommitteeonNoiseandHearingConservation,notonlythe timeof exposure and sound intensity, but alsoindividual susceptibilityisconsideredasafactorforhearinglossonset.

AccordingtoNR7,AnnexI(1998), hearinglossinduced byhighlevelsofsoundpressureisconsideredaschangesin hearing thresholds resultingfrom systematic occupational exposuretointensesound.Itsmainfeatures,irreversibility andgradualprogressionwithtimeofexposuretorisk, ini-tiallyaffectthefrequenciesof3000Hz,4000Hzor6000Hz, followedby8000Hzand500Hz,andfinally250Hz.

Incomparisonwithconventionalaudiometry,asignificant differencewasobservedbetweenG1andG2atfrequencies of250Hzinbothears and500Hzintheleftear.Although there was no significant difference for the frequency of 6000Hz, the mean pure tone air-conduction thresholds found in G1, at that frequency in both ears, were worse thanthethresholdsshownbyG2.

Thesefindingsareinagreementwithastudy24_conducted

with329musicstudents,inwhichtherewasanaudiogram notchatthefrequencyof6000Hzin78%oftheaudiometries performed.

Anotherstudy25_observed_that_20%_of_the_music_students

had music-inducedhearing loss (MIHL),andin Brazil, one study16_demonstrated_that_38.46%_of_the_music_students_had

anaudiogramsuggestiveofMIHL,followedby46.15% show-inganormalaudiogramwithnotchat3000,4000,or6000Hz. Astudy4 _performed _with _young _musicians, _aged _18---37

years, found 7% with normal audiogram and presence of notch,and24%oftheaudiogramssuggestedMIHL.

Astudy26_conducted_with₂₃_rock_musicians,_aged_21---38

years,withthemajority(57%)intheagerangebetween21 and26years,demonstratedthat,although100%oftheears hadauditorythresholdswithinnormallimits,the distribu-tionofhearingthresholdsshowedalargeconcentrationof worsethresholdsat3000,4000and6000Hz,exactlythose thatarefirstaffectedintheprocessthattriggersMIHL.

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withMIHL;thesecond study,28 _shows_21.7%;_and_the_third

study29_shows_19%._Concerning_hearing_loss_in_rock_and_jazz

bands,onestudy30_reported_52.39%_of_musicians_with_MIHL,

andregardinginstrumentalbands,onestudy31_observed_13%

ofmusicianswithMIHL;anotherstudy8_demonstrated_52.4%

withMIHL,andathirdstudy6_showed_24%_with_hearing

dis-orderssuggestiveofMIHL.

Regardingthelowerfrequencies,theliteratureshowed no findings that either corroborated or contested those foundinthisstudy.Asallparticipatinggroups(G1andG2) underwentaudiometricevaluationunderthesametest con-ditions,itissuggestedthatfurtherstudiesbeperformedto increasetheknowledgeoftheeffectsofhigh-intensitymusic onthelowerfrequencies.

Regarding the thresholds at frequencies of 3000, 4000 and 6000Hz, which, when lowered, can disclose hearing loss due to exposure to high sound pressure levels; it shouldbeemphasizedthatthisstudyobservedadifference, although not significant, between the mean conventional pure-tone air-conduction thresholds for the frequency of 6000Hz between G1 and G2, with a worse mean in G1 (Table 1). The presence of the audiometric notch, even if at only one frequency, should be seen as a warning sign, asit could suggest a trend of the onset of hearing loss.32

Stillinrelationtoconventionalaudiometry,when com-paring the right and left ears of G1, the results of this studyshowedworseresultsintheleftearfor all frequen-cies(exceptfor4000Hz),disclosingasymmetrybetweenthe ears(Table2).

Corroboratingthepresentresults,astudy33_on_the

audio-logicalprofileof40symphonicorchestramusiciansresulted inaprofilethatfollowsthepatternofMIHLevolution,but withasymmetricalterationbetweentheears,withtheleft earasthemostaffected.Twostudies27,34_reported_greater

hearing loss in the left ear,both carried out with violin-ists.However,thepresentstudyincludedtheparticipation ofonlytwoviolinstudents.

Fewstudieshavebeenreportedintheliteratureonthe use of high-frequency audiometryfor evaluation of musi-ciansandmusicstudents.Inthepresentstudy,asignificant differencebetweenG1andG2wasfound,withworseresults for G1 only at the frequency of 9000Hz in the right ear. However,themeanthresholdsat9000Hzintheleftearand at 10,000Hz and11,200Hz inboth earswereworse inG1 whencomparedtoG2,althoughnotstatisticallysignificant (Table1).

These findings differ from those of another study,4 _as

althoughtheauthorfound meanthresholdsof11dB HLat most,therewasthepresenceofanotchatthefrequency of12,500Hz bilaterally,andat thefrequencyof14,000Hz intherightear.

Inanotherstudy,16_a_notch_was_observed_at_the_frequency

of11,200Hzintheleftear,12,500Hzintherightear,and 16,000Hzinbothears;theseresultsalsodifferfromthose ofthepresentstudy.

Conversely,onestudy35_evaluated_the_temporary_change

in threshold at 500---14,000Hz in 16 non-professional musiciansbeforeandafter90minofpractice.Allhad expe-rienced repeatedexposurestointensesoundlevelsfor at leastfiveyearsduringtheirmusicalcareers.Theevaluation performedafterthepracticeshowedthelowestthresholds

for frequencies from 500Hz to 8000Hz (p<0.004), with worse results for the frequency of 6000Hz, but there werenodifferencesinthefrequenciesof9000---14,000Hz. Theauthors concluded,basedontheseresults, that high-frequencyaudiometrydoesnotappeartobeadvantageous asa means of early detection of hearing loss induced by high-intensitylevelsofmusic.

Whenanalyzed accordingtoage,for G1upto25years (Table4),althoughtherewasasignificantdifferenceonlyat frequenciesof250Hzintheleftearand500Hzinbothears, theleftearingroupG1alsoshowedtheworstmean thresh-oldsatfrequencies2000Hz,6000Hz,9000Hz,10,000Hzand 11,200Hz,whencomparedtoG2.

ForG1of26yearsandolder,therewasasignificant dif-ference only at the frequency of 250Hz in both ears and 500Hz in the left ear. However, the mean thresholds of G1werealsoworsethanG2atthefrequenciesof2000Hz, 3000Hz,4000Hz,6000Hz,8000Hz,9000Hz,10,000Hzand 11,200Hz in the left ear; and at 9000Hz, 10,000Hz and 11,200Hzintherightear(Table5).

Considering that the hearing loss induced by music or noiseoccursafteryearsofexposureandslowlyprogresses over time, the present study disclosed worse thresholds, althoughstillwithinthenormalrange,forG1atseveral fre-quencies,especiallyintheleftearforthoseolderthan26 years,whencomparedtoG2(Tables4and5).

The three institutions participating in this study offer musiccourseswithabroaddiversityofqualifications,which putsstudents inverydiverse learningsituations.Although commontoallstudents,musicalpracticeduringtraining dif-fersfromcoursetocourse,dependingontheinstitutionand thequalificationofchoiceand,inmostcases,thestudent isnotlimitedtojustonemusicalinstrument.

Inthisphase,theimplementationofahearing conserva-tionprogramforthispopulationcouldbringgreatbenefitsby providingstudentswithallthenecessaryinformationonthe risksofexposuretohigh-intensitymusicandhowtoprevent hearingloss.

Inthepresentstudy,theaudiometricfindings,although mostlywithinthe normalrange,did notrule outpossible earlycochleardamage,whichwereperceivedwhen appro-priatecomparisonsweremade,showingthat thegroupof students (G1) exposed to music almost daily had worse pure-tone air conduction thresholds in the conventional audiometryand athigh frequencies, especiallyinthe left ear(Table1).

High-frequency audiometry is a useful tool to detect earlycochlearalterations.Despitethelackofstandardized normalityparametersandthefactthattheyarerarely per-formedinmusicians,thedifferencesinauditorythresholds athighfrequencies,iffollowedforalongerperiodoftime andalso associatedwithconventional hearing thresholds, canprovideinformationonthehearingstatusofmusicians overtheyears.

Theappearanceofaudiometricnotchesinboth conven-tionalandhigh-frequency audiometrycouldbetter clarify theeffectsofhigh-intensitymusic.

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areneitherstrongenoughnorofsufficientdurationtoresult inhearingdamage.

Conclusion

Bothconventionalandhigh-frequencyaudiometrydisclosed statistically significant differences when comparing the audiometric thresholds of the music student group and thegroupconsistingofnon-musicians,non-musicstudents, and those not exposed to noise at work, with the worst thresholdsfound inthegroupofmusicstudents.Themost significantdifferenceswerefoundintheevaluationofhigh frequencies, which allowsfor the inference that sporadic high-frequencythresholdassessmentcanbeusefulinearly detectionofhearinglossinmusicians.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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