www.bjorl.org
Brazilian
Journal
of
OTORHINOLARYNGOLOGY
ORIGINAL
ARTICLE
Electroacoustic
verification
of
frequency
modulation
systems
in
cochlear
implant
users
夽
Vanessa
Luisa
Destro
Fidêncio
a,∗,
Regina
Tangerino
de
Souza
Jacob
a,
Liége
Franzini
Tanamati
b,
Érika
Cristina
Bucuvic
b,
Adriane
Lima
Mortari
Moret
aaUniversidadedeSãoPaulo(USP),FaculdadedeOdontologiadeBauru(FOB),DepartamentodeFonoaudiologia,Bauru,SP,Brazil bUniversidadedeSãoPaulo(USP),HospitaldeReabilitac¸ãodeAnomaliasCrânio-Faciais(HRAC),Bauru,SP,Brazil
Received21August2017;accepted26November2017 Availableonline26December2017
KEYWORDS Cochlearimplant; Assistivetechnology; Speechperception; Pediatric Abstract
Introduction:Thefrequencymodulationsystemisadevicethathelpstoimprovespeech per-ceptioninnoiseandisconsideredthemostbeneficialapproachtoimprovespeechrecognition in noise in cochlear implant users. According to guidelines, there is a need to perform a checkbeforefittingthefrequencymodulationsystem.Althoughtherearerecommendations regardingthebehavioralteststhatshouldbeperformedatthefittingofthefrequency mod-ulationsystemtocochlearimplantusers,therearenopublishedrecommendationsregarding theelectroacoustictestthatshouldbeperformed.
Objective:Performanddeterminethevalidityofanelectroacousticverificationtestfor fre-quencymodulationsystemscoupledtodifferentcochlearimplantspeechprocessors.
Methods:Thesampleincluded40participantsbetween5and18year’susersoffourdifferent modelsofspeechprocessors.Fortheelectroacousticevaluation,weusedtheAudioscanVerifit devicewiththeHA-1 couplerandthelistening checkdevicescorrespondingtoeachspeech processormodel.Incaseswherethetransparencywasnotachieved,amodificationwasmade inthefrequencymodulationgainadjustmentandweusedtheBrazilianversionofthe‘‘Phrases inNoiseTest’’toevaluatethespeechperceptionincompetitivenoise.
Results:Itwasobservedthattherewastransparencybetweenthefrequencymodulationsystem andthe cochlearimplant in85%of theparticipants evaluated. Afteradjusting thegainof thefrequencymodulationreceiverintheotherparticipants,thedevicesshowedtransparency when theelectroacoustic verificationtest wasrepeated. Itwasalso observed thatpatients demonstratedbetterperformanceinspeechperceptioninnoiseafteranewadjustment,that is,inthesecases;theelectroacoustictransparencycausedbehavioraltransparency.
夽 Pleasecitethisarticleas:FidêncioVL,JacobRT,TanamatiLF,BucuvicÉC,MoretAL.Electroacousticverificationoffrequencymodulation systemsincochlearimplantusers.BrazJOtorhinolaryngol.2019;85:162---9.
∗Correspondingauthor.
E-mail:vanessa.destrof@gmail.com(V.L.Fidêncio).
PeerReviewundertheresponsibilityofAssociac¸ãoBrasileiradeOtorrinolaringologiaeCirurgiaCérvico-Facial.
https://doi.org/10.1016/j.bjorl.2017.11.001
1808-8694/©2017Associac¸˜aoBrasileiradeOtorrinolaringologiaeCirurgiaC´ervico-Facial.PublishedbyElsevierEditoraLtda.Thisisanopen accessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).
Conclusion: Theelectroacousticevaluationprotocolsuggestedwaseffectiveinevaluationof transparencybetweenthefrequencymodulationsystemandthecochlearimplant.Performing theadjustmentofthespeechprocessorandthefrequencymodulationsystemgainareessential whenfittingthisdevice.
© 2017 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Published by Elsevier Editora Ltda. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
PALAVRAS-CHAVE
Implantecoclear; Tecnologiaassistiva; Percepc¸ãodafala; Pediatria
Verificac¸ãoeletroacústicadesistemasdefrequênciamoduladaemusuáriosde implantecoclear
Resumo
Introduc¸ão: O sistema de frequência modulada é um dispositivo que ajuda a melhorar a percepc¸ãodafalanoruído,eéconsideradoaabordagemmaisbenéficaparamelhoraro recon-hecimentodafalanoruídoemusuáriosdeimplantescocleares.Deacordocomasdiretrizes,é necessáriorealizarumaverificac¸ãonomomentodaadaptac¸ãodosistemadefrequência mod-ulada.Emboraexistamrecomendac¸õessobreostestescomportamentaisaseremrealizadosna adaptac¸ãodosistemadefrequênciamoduladaparausuáriosdeimplantescocleares, nãohá recomendac¸õespublicadassobreotesteeletroacústicoquedeveserrealizado.
Objetivo: Realizarevalidarumtestedeverificac¸ãoeletroacústicaparasistemasdefrequência moduladaacopladosadiferentesprocessadoresdefaladeimplantecoclear.
Método: A amostra incluiu40 participantes com idadesentrecinco e18 anos,usuários de quatro modelosdeprocessadoresde fala.Paraaavaliac¸ãoeletroacústica,utilizou-se o dis-positivo Audioscan Verifitcom oacoplador HA-1 eos dispositivos de verificac¸ãode escuta correspondentes acada modelode processadorde fala. Nos casos em quea transparência nãofoialcanc¸ada,foirealizadaumamodificac¸ãonoajustedoganhodosistemadefrequência moduladae,emseguida,aplicou-seaversãobrasileirado‘‘PhrasesinNoiseTest’’paraavaliar apercepc¸ãodafalacomruídocompetitivo.
Resultados: Observou-sequehouvetransparênciaentreosistemadefrequênciamoduladae oimplantecoclearem85%dosparticipantesavaliados.Depoisdeajustaroganhodo recep-tor dosistema defrequência moduladanosoutrosparticipantes, osdispositivos mostraram transparênciaquandootestedeverificac¸ãoeletroacústicafoirepetido.Observou-setambém ummelhordesempenhonapercepc¸ãodafalanoruídoapósumnovoajuste,ouseja,nesses casosatransparênciaeletroacústicaresultouemtransparênciacomportamental.
Conclusão:Oprotocolodeavaliac¸ãoeletroacústicasugeridofoieficazparaavaliara transparên-ciaentreosistemadefrequênciamoduladaeoimplantecoclear.Arealizac¸ãodoajustedo processadordefalaeoganhodosistemadefrequênciamoduladasãoessenciaisnomomento daadaptac¸ãodestedispositivo.
© 2017 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Publicado por Elsevier Editora Ltda. Este ´e um artigo Open Access sob uma licenc¸a CC BY (http:// creativecommons.org/licenses/by/4.0/).
Introduction
FromJanuary1992toJanuary2017,7893cochlearimplant surgeries were carried out in the Unified Health System accreditedservicesinBrazil.1Inthistimeframe,thedevice
manufacturers invested in new technologies in order to providemaximum effectivenessandaccessibilitytousers, such as new signal processing strategies and directional microphonetechnologies,inanattempttoimprovespeech perceptioninnoise.2---5Thefrequencymodulation(FM)
sys-tem is a device that enables speech perception in noise by reducing the harmful effectsof reverberation and the distance between the speakerand the listener.6,7 The FM
systemiscurrentlyconsideredthemosteffectiveapproach
toimprovespeechrecognitioninnoiseincochlearimplant users.8
TheFMsystemwasintroducedintheUnifiedHealth Sys-teminBrazilonJune25,2013,throughOrdinanceno.12749
andisintended for individualsbetween 5and 18yearsof age.Subsequently, the hearinghealth services accredited bytheUnifiedHealthSystemthroughoutthecountryhave beenpreparedtocarryoutFMfitting.
Guidelinestoassistaudiologistsintheselection,fitting, andverificationoftheFMsystemforchildrenrequiring hear-ing aids have been made available.10 According to these
guidelines,performing a carefulcheck is required before fittingtheFMsystemtohearing-impairedchildren.The elec-troacoustictest recommendedfor hearingaidsadoptsthe
concept of transparency between the FM system and the hearingaid.
Although there are recommendations regarding the behavioral tests that should be performed at the fitting the FM system to cochlear implant users,10 there are no
publishedrecommendations regarding the electroacoustic test. Indeed,thereis only onereport suggesting the per-formanceofanelectroacousticverificationprotocolof FM systemcoupledtothecochlearimplantfortheassessment ofthetransparencybetweenthedevices.11
Consideringthateachchildwithacochlearimplanthas itsownpaceoforallanguagedevelopment,whichisrelated tointrinsicandextrinsicfactors,asignificantnumberof chil-drenmaynotbeabletoreportthebenefitofcouplingthe FMsystemtothecochlearimplantonlythroughbehavioral measures. Thus, it is necessary to implement a thorough protocol that includes objective tests for electroacoustic verification,inordertoachievethebestuseandtofitthe deviceaccuratelyregardlessofthechild’sresponse.
Byprovidingthisrealbenefittothepatient,itisexpected thattheadherencetotheuseoftheFMsystemwillincrease. Thus,inadditiontotheindividualbenefits,the implemen-tationofathoroughprotocolwillalsohaveapositiveimpact on the public policies of hearing health care in Brazil. Indeed,theFMsystemisanexpensivedevice,anditisthus essentialthatthehearinghealthservicesareenabledto per-formaccuratefittinginordertoavoidnegativeimpactson theusersandthepublicmoney.
Methods
The study was carried out in the Craniofacial Anomalies Rehabilitation Hospital, University of São Paulo, Bauru, São Paulo, Brazil and began once the approval of the ResearchEthicsCommitteewasobtained,underopinionno. 1,992,217.
Caseselection
Thesampleincluded40participantsbetweentheagesof5 and18years,whowereusersofthefollowingspeech pro-cessors:Harmony(15%),Opus2(60%),Freedom(7.5%),and Nucleus5(17.5%).Theparticipantswereselectedaccording tothedemandofattendancesoftheCraniofacialAnomalies RehabilitationHospitalinwhichtheresearchwascarriedout fromNovember2015toAugust2016.Theresearcher respon-siblefordatacollectionvisitedtheresearchsiteduringthe daysandtimeswhentherewererequestsforadaptationof theFMsystem.Hence, hepersonallyselectedthe partici-pantsforthestudyandprovidedclinicalcare.
Thefollowinginclusioncriteriawereestablished: - Childrenbetween5and18yearsofage;
- Childrenwithestablishedordevelopingorallanguage; - Effectivecochlearimplantusersforatleast3years; - Nootherimpairmentsassociatedwithhearing.
Speechprocessoradjustment
ForthefittingoftheFMsystem,thespeechprocessorswere adjustedinrelationtotheaudio-mixing,followingthe rec-ommendationsofSchaferandWolfe.12
AdjustmentoftheFMsystem
The assessments were performed upon fitting of the FM system, and all participantsreceived the Phonak-branded Inspiro Premium FM transmitter. All the fitted receivers consistedofelectricalcouplingandvariedaccordingtothe speech processor model. Users of the Harmony and Opus 2 speech processorsreceived the MLxi universal receiver, which wascoupledtotheformer usingtheiConnecthook and to the latter using the battery cover with the FM entry.UsersoftheFreedomandNucleus5speech process-orsreceivedspecificreceivers,usingtheMicrolinkFreedom modelfortheformerandtheML14iforthelatter.
The FMreceivers of the40 participants wereadjusted using the Phonak ‘‘FM SuccessWare’’ software, version 4.6.3,whichautomaticallycalculatesthegainaccordingto the speechprocessormodel. Table1 summarizesthe gain settingsusedforeachspeechprocessormodel.
Electroacousticevaluation
Anelectroacousticevaluationwasperformedforall40 par-ticipants.Forthisevaluation,weusedtheAudioscanVerifit devicewiththeHA-1couplerandthelisteningcheckdevices correspondingtoeachspeechprocessormodel.Wealsoused asoundattenuationboxmadebyafoam-linedplasticbox.
In this methodology, the electroacoustic verification test was used toevaluate the transparency between the FM system and the cochlear implant as suggested by Schafer et al.11 The step-by-step process is depicted in
Tables2and3.
According to the above-mentioned study, the devices with difference between the means of the evaluated frequenciesequaltoorlessthan3dBwereconsidered trans-parent.Incaseswherethetransparencywasnotachieved, i.e.,whenthedifferencebetweenthemeans wasgreater
Table1 FMgainrecommendedforeachspeechprocessormodelautomaticallycalculatedbythePhonak‘‘FMSuccessWare’’ software,version4.6.3.
Speechprocessormodel Brand FMgainrecommended
Harmony AdvancedBionics +10dB
Freedom Cochlear 0dB
Nucleus5 Cochlear +2dB
Table2 Step1:step-by-stepelectroacousticevaluationtest---IConly.
a ConnecttheICspeechprocessortoitsrespectivelisteningcheckdevice
b Placeonesideoftheearphone(listeningcheckdevice)ontheHA-1couplerthroughtheuseof
puttyandplacethemintheVerifittestbox
c IntheVerifitchoose:‘‘test’’---‘‘testboxmeasures’’---‘‘speechmap’’
d PlacetheICspeechprocessorinthetestboxwiththemicrophonenexttothereference
microphone(Verifit)
e Closetheequipmentandselectthestimulusintensity65dBSPLandstimulustype‘‘Speech-ISTS’’
f Writhedownthevaluesobtainedinthefrequenciesof750,1000and2000Hzandcalculatea
meanofthesevalues
Table3 Step2:step-by-stepelectroacousticevaluationtest---IC+FMsystem.
a AdjustthegainofFMsystem(company’ssoftware)
b PlugtheFMsystemreceiverintolisteningcheckdeviceofthespeechprocessor c Toputthespeechprocessorinthesoundattenuationbox
d PutthemicrophoneoftheFMsystemtransmitterinthetestbox(Verifit)nearthereferencemicrophone e IntheVerifitchoose:‘‘test’’---‘‘testboxmeasures’’---‘‘speechmap’’
f Closetheequipmentandselectthestimulusintensity65dBSPLandstimulustype‘‘Speech-ISTS’’
g Writhedownthevaluesobtainedinthefrequenciesof750,1000and2000Hzandcalculateameanofthesevalues
than 3dB, a modification in the FM gain adjustment was madeusingPhonak‘‘FMSuccessWare.’’
Evaluationofspeechperception
Thespeechperceptiontestwasperformedincaseswhere electroacoustictransparencywasnotachievedandFM sys-temgainadjustmentneededtobemodifiedinordertoverify if electroacoustic transparency causes behavioral trans-parency.Thiswasdone becausetherewouldbenowayto otherwisecomparetwotestsituationsofspeechperception, becauseFMgainadjustmentdoesnotneedtobemodified incaseswithtransparencybetweenthedevices.
Thetestusedtoassessspeechperceptionincaseswhere transparency wasnotachievedwasthe‘‘Phrases inNoise Test(PINT)---Brazilian version’’13 becauseit isoneof the
testsindicatedfortheassessmentofspeechperceptionin competitivenoiseforyoung children,particularlyfor chil-drenwhoarestilldevelopingtheirorallanguageskills.
TheBrazilianversionofthePINTtest,13includes10
sim-plesentences relatedtobody parts, presented at afixed intensity of 60dB SPL,and withclassroom noise intensity varyingfrom45to72dBSPLinscalesof3dBand8s inter-stimulusinterval.Thus,theteststartsindescendingSignal to Noise Ratio (SNR) from +15dB to−12dB, and endsin ascendingSNRfrom−12dBto+15dB.
Statisticalanalysis
Descriptivestatisticalanalysiswasperformedforallmodels andbrandsofthecochlearimplants.Thecomparisonofthe resultsoftheelectroacousticevaluationbetweendifferent brands and models wasperformed using analysis of vari-ance(ANOVA).Comparisonoftheelectroacousticevaluation resultsinthe‘‘implantonly’’and‘‘implant+FM’’conditions wasperformedusingthepairedt-test.
Theresultsofthespeechperceptiontestwerenot ana-lyzedstatisticallybecauseofthesmallsamplesize.Thus,it wasimpossibletoconcludethatthedifferencebetweenthe twoassessed situations wasstatistically significant. Thus, weoptedforthequalitativeanalysisoftheseresults.
Results
Table4summarizestheresultsoftheelectroacoustic veri-ficationprocedure (transparencyevaluation).Wedetected transparency between the FM system and the cochlear implantin 34 (85%) of the 40 participants. The results in whichnotransparencywasobservedarehighlightedinbold inTable4.
BasedonANOVA,therewasnostatisticallysignificant dif-ferencebetweenthevaluesoftransparency(mean)inthe differentbrands(p=0.545)andmodels(p=0.327).
Table5summarizestheresultsofthecasesinwhichthere wasnotransparencybetweenthedevices,andtheresults aftermodifyingtheFMgainadjustmentusingthe‘‘FM Suc-cessWare’’software.
AfteradjustingthegainoftheFMreceiver,thedevices of participants 4, 15, 16, and 18 exhibited transparency when the electroacoustic verification test was repeated. Furthermore,participants 4, 16, and 18 exhibited a bet-terperformanceinspeechperceptioninnoiseafteranew adjustment;thus,inthesecases,theelectroacoustic trans-parencycausedbehavioraltransparency.
Inthecaseofparticipant15,theFMgainwasmodified andanewelectroacousticverificationwasperformed. How-ever,thespeechperceptioninnoisecouldnotbeperformed owingtotheleveloflanguagedevelopment.Indeed, partic-ipant15couldnotperformtheBrazilianversionofthe Hear-inginNoiseTest(HINT),14whichhadbeensuggestedinthe
initialmethodology.Itshouldbenotedthattheevaluation ofthisparticipantwasperformedatthebeginningofdata
Table4 Resultsoftheelectroacousticevaluation.
Participant Speechprocessormodel MeanofCImicrophone(dB) MeanofCI+FMmicrophone(dB) Difference(dB)
1 Harmony 74.6 75 0.4 2 79 78 1 3 78.3 80.3 2 4 75 79.3 4.3 5 87 85.3 1.7 6 81.3 80.6 0.7 7 Opus2 72.6 75.6 3 8 67.6 69 1.4 9 71 74.6 3.6 10 72 75 3 11 73.3 71.3 2 12 74 73.6 0.4 13 78.6 77.3 1.3 14 75.3 74.4 0.9 15 68.6 64 4.6 16 73 76.6 3.6 17 64.6 67.3 2.7 18 78.6 82 3.4 19 72.6 75.3 2.7 20 66 67.3 1.3 21 77.3 78 0.7 22 74 75 1 23 70.6 72.6 2 24 79.6 82 2.4 25 54 53.6 0.4 26 78 79.6 1.6 27 78.6 80.6 2 28 71.6 74.6 3 29 70.6 71.6 1 30 73 76 3 31 Freedom 75.3 76.6 1.3 32 73.6 76 2.4 33 68.6 75 6.4 34 Nucleus5 71.3 68.6 2.7 35 65.6 67.3 1.7 36 73.3 70.3 3 37 78.6 76.3 2.3 38 69.6 72 2.4 39 70 69.6 0.4 40 84.3 82.6 1.7
CI,cochlearimplant;FM,frequencymodulationsystem.
collectionand,therefore,beforesendingtheamendmentto theResearchEthicsCommitteerequestingtheinclusionof thePINTtest.13 inthemethodology.Participant15didnot
returntotheserviceuntiltheendofthisdataacquisition. In the case of participant33, for whom there was no electroacoustictransparencyof theFMsystem coupledto thecochlearimplant,themodificationinthereceivergain adjustmentreducedtheFMsystemgain.Participant33used theFreedomspeechprocessor,forwhichthemanufacturer oftheFMsystemPhonakrecommendsthattheFMreceiver gainbesetto0dB(Table4).Therefore, adjustingthe FM gaincouldnegativelyaffecttheFMsystembenefitforthis participant.
Participant 9, for whom there was no electroacoustic transparency of the FM system coupled to the cochlear implant,didnotremainlongenoughintheoutpatient rou-tinetoperformtheproceduresofFMgainadjustmentand speechperceptiontest.
Discussion
The results shown in Table 4 reflect the importance of performing electroacoustic verification of the FM system coupled to the cochlear implant, considering that trans-parencywasachievedin85%of thecases.This resultcan
Table5 DescriptionoftheresultsbeforeandafternewFMgainadjustment. P Initialgain(dB) Resultofthe
electroacoustic evaluationa(dB) Speechperception innoisetesta(dB) Gainafter adjustment(dB) Resultofthe electroacoustic evaluationb(dB) Speechperception innoisetestb(dB) 4 +10 4.3 0 +8 1.7 −1.5 9 +10 3.6 --- --- --- ---15 +10 4.6 --- +12 1.3 ---16 +10 3.6 +6 +8 2 −1.5 18 +10 3.4 0 +8 0.3 −1.5 33 0 6.4 --- --- --- ---P,participant. a Withinitialgain. b Afteradjustmentofgain.
beexplainedbythefactthatthestrictadjustmentof the speechprocessorsandFMgainwasperformed thoroughly. Although the FMsystems areconceptually simple in their technologies and handling, one majorchallenge in fitting them is theneed tostrike a properbalance between the gainsofthissystemandthoseofthehearingaid.10
FM system technology has stimulated the initial ques-tions,forexample,whetheramonauralfittingisbetterthan abinauralone,andsuggestedquestionsrelatedto adjust-mentsperformed in the speechprocessor of thecochlear implantandinthereceiveroftheFMsystemduringfitting.15
A study in adults using unilateral cochlear implants con-cluded thatFMreceivergainhas thepotentialtodirectly influencespeechrecognitioninnoise.16Anotherstudy
com-paredspeechrecognitionin noisein adolescentandadult users of FM systems electrically and electromagnetically coupledto cochlear implants.The findingsindicated that differentFMgainadjustmentsmayberequiredtoachieve optimal performance.17 Clinical studies have shown that
gain adjustments in wireless communication systems can haveaconsiderableeffectontheperformanceoftheusers ofthesedeviceswhencoupledtothecochlearimplant.18
The speechrecognition in noisetest ‘‘Phrases inNoise Test’’ (PINT)13 wasperformed in threeout ofthe 6 (15%)
cases in which transparency was not achieved (Table 4).
Table 5 indicates a better performance of the three par-ticipants in the PINT13 test after the new adjustment of
the receiver gain when the devices were set up in order to achieve transparency. Based on this, we can suggest thatelectroacoustictransparencycausedbehavioral trans-parency. These participantsneeded a newgain setting to obtain greater benefit from the FM system, thus proving thattheeffectivebenefitisdirectlyrelatedtoanadequate adjustmentofthereceivergain,whichisinlinewith pre-viousstudies.11,18Consideringthatthesethreeparticipants
weretheyoungestinthepresentstudyandwere develop-ingtheirlanguageskills,theneedforthisnewadjustment wasonlyrealizedaftertheelectroacousticverificationtest. Thus, it is perceived that the use of a thoroughprotocol duringthefittingoftheFMsystemtothecochlearimplant inchildren,includingobjectivetestsinadditionto behav-ioraltests,isessentialtoensureeffectivemeasurementand fitting.
Aprevious studyevaluatedthefrequencyofuseof the FMsystemin70usersofcochlearimplantsintheclassroom.
Atotalof52.8%saidtheydidnotuseorpartiallyusedthe device.Thus,althoughtheliteraturereportstheadvantages ofusingtheFMsystem,therearestillpatientswhoownthe deviceanddonotuseit.Theauthorsfoundthat10%outof the52.8%ofthepatientswhodidnotuseoftheFMsystem effectivelystatedthattheydidnotperceiveanybenefitin theFMsystem.Itcanbeaffirmedthattheproperadjustment oftheFMsystemisdirectlyrelatedtothegreaterbenefitof thetechnologyand,therefore,tothegreateradherenceto itsuse.Thus,inadditiontoprovidingaproperfitting,the electroacousticverificationtest,whenrelatedtoincreasing adherencetotheuseof FMsystems,canpositivelyaffect thepublicpoliciesrelatedtograntingthisdevicetocochlear implantusers,thuspotentiallyavoidingthewasteofpublic funds.19
As discussed previously, there is only one previous report on the development of an electroacoustic evalua-tionprotocolforFMsystemscoupledtocochlearimplants.11
The authors evaluated transparency in three models of speechprocessors: Harmony, Opus 2, and Nucleus 5, and madedifferent combinations usingPhonak andOticon FM transmitters. Thus, the discussion of the data shown in
Tables1and2iscomparativelybasedontheresultsreported inthispreviousstudyregardingtheuseoftheInspiro trans-mitterandMLxireceptors,bothPhonak-branded,whichare thesameusedinourstudy.
Table4indicatesthatonly1(16.6%)ofthesixtests per-formed on the Harmony speech processor model did not showtransparency.Itwasnecessarytoadjustthe FMgain in the case of participant 4, in which the gain of +10dB was reduced to +8dB in order to achieve transparency (Table5).Theabove-mentionedstudy11 established
combi-nationsamongthreedifferentreceiversandfourdifferent transmittersfor the test withthesame speechprocessor. Theauthorsreportedthat,whenusingtheInspiro transmit-terwiththeMLxireceivercoupledtotheHarmony speech processor, transparency wasachieved with gain of +4dB. ThisvariabilityoftheFMgainadjustmenttoachieve trans-parencymayoccur,butthespeechperceptiontestmustbe performedtoverifyifthebenefitismaintained.
For the tests performed with the 24 users of Opus 2 speechprocessors,therewasnotransparencyin4(16.6%) cases.Fromthese,itwaspossibletoperformanew adjust-mentintheFMgaininthreecases.AsshowninTable5,it wasnecessarytoincreasetheFMgainfrom+10dBto+12dB
forparticipant15inordertoachievetransparency.For par-ticipants16and18,itwasnecessarytodecreasetheFMgain from+10dBto+8dB.Theseresultsareinlinewithprevious data.11 The evaluation withthe Opus 2 speech processor
indicatedthatvariablegainsettingswerenecessaryinorder toachievetransparency.Inparticular,inthecombinationof theMLxireceiverand theInspiro transmitter,theauthors found that the FMgain required to achieve transparency was0dB.In83.4%ofthecasesthatpresentedtransparency withouttheneedofanewadjustment,itwasobservedthat therewasadifferenceof10dBbetweentheresultsfound inthepresent studyandtheresults foundin theprevious study.11
Theinterestofthisstudyliesinthefactthattheresults indicatedavariabilityintheFMgainadjustmentwhenthe samespeechprocessormodelwascoupledtothesameFM systemtechnology,butwithdifferentusers(n=33),except for theNucleus5 speechprocessor model. This isin con-trasttothefindingsreportedintheUnitedStates,11 which
pointedtovariabilityintheFMgainadjustmentwhena sin-gle speechprocessor was coupledto differentFM system technologies.
RegardingtheelectroacousticevaluationoftheFM sys-tem coupled to the Nucleus 5 speech processor, Table 4
showsthattransparencywasachievedintheseven(100%) cases with FM gain at +2dB, with no need for a new adjustment.The gainsettingsthat areneeded toachieve transparency have been previously reported to be highly variable in a study combining four transmitters and four receivers for the evaluation of transparency with the Nucleus 5 speech processor.11 Regarding the use of the
Inspiro transmitter combined withthe use of the Phonak receivers,theauthorsreportedthatitwasnotpossibleto achievetransparencywhenusingtheMLxSreceiver,a pre-viousgenerationreceiver.FortheuseoftheMLxireceiver, itwasnecessary toadjustthe FMgainto+8dB for trans-parency.Comparingtheresultsobtainedinthepresentstudy with those obtained in the aforementioned study, a 6dB differencewasobservedinthegainneededtoachieve trans-parency. However, it is noteworthy that this study used theML14i receiver,aspecificdevicefor connectiontothe Nucleus5speechprocessor. Thus,the differencebetween thegain settingscan be explainedby thefact that those authorsusedauniversalreceiver,whichrequiresanadapter tobeconnectedtothecochlearimplant.Thus,thereceivers used differed in the connection mode. In this study, all FM receivers coupled to the Nucleus 5 speech processor belongedtospecificmodels.
Insummary,owingtothevariabilityfoundintheFMgain settingstoachievetransparency,itishighlyrecommended toperformtheelectroacoustic verificationtest of the FM systemwhencoupledtothecochlear implant,particularly inchildren.Itisbelievedthatthetransparencybetweenthe FMsystem and thecochlear implant canpositively affect theadherencetotheuseoftheFMsystem,andwill conse-quentlyaffectthebestuseofpublicmoneyinrelationtothe grantingofthisdevicebytheBrazilianUnifiedHealth Sys-tem.Indeed,between2013and2017,16,141FMsystemKits weregrantedunderOrdinance1274.9Thelongitudinal
mon-itoringof theseparticipantsinfuturestudiesmayprovide morespecificinformationabouttheiradherencetotheuse oftheFMsystem.
Conclusions
Basedonthepresent findings,weconcludethe following: (1)The electroacousticevaluationprotocol suggestedwas effectiveinevaluatingtransparencybetweentheFMsystem andthedifferentmodelsofspeechprocessorsofcochlear implants; (2) There was a greater benefit in the speech recognitioninnoisewhentherewasatransparencybetween theFMsystemandthecochlearimplant;(3)Adjustingthe FM system gaincan be very helpful for many cases when fittingthisdevice.
Funding
The research reported in this publication was supported by the Coordination of Superior Level Staff Improvement (CAPES) and by São Paulo Research Foundation (FAPESP) grantno.2014/20398-1.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
Acknowledgment
WethankProf.Dr.JoséRobertoPereiraLauris,for perform-ing the statistical analysis; and to Dr. Erin Schafer, from Texas, for having made available via e-mail information regarding the procedure used in the methodologyof this study.
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