A multicentre clinical evaluation of paediatric cochlear implant users upgrading to the Nucleus® 6 system

A

multicentre

clinical

evaluation

of

paediatric

cochlear

implant

users

upgrading

to

the

Nucleus

1

6

system

Anke

Plasmans

,

Emma

Rushbrooke

,

Michelle

Moran

,

Claire

Spence

,

Leen

Theuwis

,

Andrzej

Zarowski

_,

_Erwin

_Offeciers

_,

_Beth

_Atkinson

_,

_Jane

_McGovern

_,

_Dimity

_Dornan

_,

Jaime

Leigh

,

Arielle

Kaicer

,

Rod

Hollow

,

Leigh

Martelli

,

Valerie

Looi

,

Esti

Nel

,

Janine

Del

Dot

,

Robert

Cowan

**

,

Stefan

J.

Mauger

*

a

EuropeanInstituteforORL-HNS,SintAugustinusHospital,Antwerp,Belgium

b_{HearandSay,Brisbane,Australia}

c_{RoyalVictorianEyeandEarHospital,Melbourne,Australia} d

TheHearingHouse,Auckland,NewZealand

e

TheHEARingCRC,Melbourne,Australia

f

SCICCochlearImplantProgram,anRIDBCservice,Sydney,Australia

g

TheDepartmentofAudiologyandSpeechPathology,theUniversityofMelbourne,Melbourne,Australia

h

CochlearTechnologyCentreBelgium,Mechelen,Belgium

i_{CochlearLimited,Sydney,Australia} j_{CochlearLimited,Melbourne,Australia}

ARTICLE INFO Articlehistory:

Received12November2015

Receivedinrevisedform5February2016 Accepted6February2016

Availableonline21February2016 Keywords:

Children Cochlearimplant Noisereduction

Automaticsceneclassification Speechperception

Directionalmicrophones

ABSTRACT

Objectives:Theaimofthisstudywastoinvestigatewhetherexperiencedpaediatriccochlearimplant

userscouldshowbenefitstospeechperceptionoutcomesfromtheintroductionofnoisereductionand

automated scene classification technologies as implemented in the Nucleus1

6 sound processor.

Previousresearchwithadultcochlearimplantusershadshownsignificantimprovementsinspeech

intelligibilityforlisteninginnoisyconditionsandgooduseracceptanceforupgradingtotheNucleus6

processor.Inadults,theseimprovementsforlisteninginnoisewereprimarilyattributedtotheuseofa

range ofnew input processing technologies includingnoise reduction, as well asintroduction of

automaticsceneclassificationtechnology.

Methods:Experiencedpaediatriccochlearimplantusers(n=25)wererecruitedfromfourclinicslocated

inthreecountries.Researchparticipantswereevaluatedonthreeoccasions,aninitialsessionusingtheir

Nucleus 5sound processor;asecondsession in whichparticipantsused theNucleus 6processor

programmedwiththesametechnologiesaswereusedintheirNucleus5soundprocessor;andafinal

sessioninwhichparticipantsusedtheNucleus6processorprogrammedwiththedefaulttechnologies

including automatic scene classification (SCAN) which automatically selects the microphone

directionality,noisereduction(SNR-NR),andwindnoisereduction(WNR)technologies.Priortoboth

thesecond and thirdevaluations, researchparticipants had approximately two weeks take-home

experience with the new system. Speech perception performances on monosyllabic word tests

presentedinquietandinnoise,andasentencetestpresentedinnoise,werecomparedacrossthethree

processorconditions.AcceptanceoftheNucleus6defaultsettingswasassessedinafinalsession.

Results:No group meandifferencein performance was foundfor monosyllabicwords inquiet. A

significantimprovementinspeechperceptionwasfoundforbothmonosyllabicwordsandsentencesin

noisewiththedefaultNucleus6programconditionascomparedwiththeNucleus5condition.No

acceptanceissueswerenotedforanyofthechildren.

Conclusions: Experiencedpaediatriccochlearimplantusersshowedasignificantimprovementinspeech

perceptioninlisteninginnoisewhenupgradedtotheNucleus6soundprocessorprimarilyduetothe

* Correspondingauthorat:CochlearLimited,Level1,174VictorianPde,EastMelbourne,Victoria,Australia. ** Correspondingauthorat:TheHearingCRC,550SwansonSt,Carlton,Victoria,Australia.

E-mailaddress:[email protected](S.J.Mauger).

ContentslistsavailableatScienceDirect

International

Journal

of

Pediatric

Otorhinolaryngology

j ou rna l h ome pa ge : w ww . e l se v i e r. co m/ l oc a te / i j porl

http://dx.doi.org/10.1016/j.ijporl.2016.02.004

0165-5876/ß2016TheAuthors.PublishedbyElsevierIrelandLtd.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense( http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction

Theworldisanincreasinglynoisyenvironment,andevidence suggeststhatchildrenspendapproximately30%oftheirtimeeach day in noise [1]. One such noisy environment, commonly experiencedbychildren,istheschoolclassroom.Theunfavourable signal-to-noiselevelsregularlypresentinclassroomenvironments canoftenleadtoproblemswithunderstandingspeech.Studiesof children aged six through 11 years old with normal listening abilitieshavesuggestedthattheyrequirea15–20dBbetter signal-to-noiseratiothanadultstoachievesimilarlevelsof understand-ing[2].Thedeleteriouseffectsofnoisyenvironmentsarefurther pronouncedwithcochlearimplant(CI)recipientswhocanfindit evenmoredifficult tounderstand speech innoise compared to their normal-hearing peers [3]. Due to the diversity of noisy environmentsandthesignificantperiodsoftimechildrenspendin them,thepotentialtoprovidearangeoftechnologies aimedat improving listening performance in these challenging environ-mentsmaybehighlybeneficial.

1.1. Currentapproachestosignalmanagement

Anumberofapproachestosignalmanagementhavepreviously beenimplemented in Nucleus1

cochlear implant systems, and widely used by paediatric CI recipients. Automatic Sensitivity Control(ASC)isaslow-actingcompressordesignedto automati-callyreducethelevelofnoisepresentininputsignalsreceivedat themicrophoneinanoisyenvironment[4,5].Incontrast,adaptive dynamicrangeoptimization(ADRO)isamulti-channeltechnology thatcontinuouslyadjustseachchannelsgaintoplacetheoutput signaloptimallywithintheelectricalhearingdynamicrange[6]. Anothercommon approachtosignalmanagement istheuseof directionalmicrophoneswhich enable thelistener tomanually selectaconfigurationthatbestretainsspeechinformationarriving fromin-frontoflisteners,whileattenuatingnoisearrivingfrom otherdirections.

1.2. Newapproachestoimprovinglisteningperformance

Recently, new sound processing technologies have been introducedandevaluatedinstudiesofadultCIusers[7].Automatic scene classification aims to remove the need for manual adjustment by the user by automatically selecting appropriate inputprocessingtechnologiesforeachspecificlistening environ-ment.Thiscouldpotentiallybeofparticularbenefittopaediatric users, who are either unable to or have difficulty in changing programs. For example, automatic scene classification can automaticallyselectasuitabledirectionalmicrophonetechnology withoutuser input as theymove from the classroom into the playground, two very differentlistening environments encoun-teredalmostdailybychildren.InstudieswithadultCIusers,the automaticsceneclassificationinNucleus6(SCAN)wasfoundto provideamean3.5dBimprovementinspeechunderstandingas comparedtotheNucleus5defaultprogram[7].

A background noise reduction technology has also recently been developed and introduced into the Nucleus 6 speech processor.Thistechnologyaims toreduceconstantbackground noiseandenhancelisteninginchallengingsignal-to-noise condi-tions. Clinical trials of these background noise technologies by

experienced adult cochlear implant users have demonstrated significant improvements in speech understanding in noisy environments [8,9]. In addition, results have shown significant improvements in listening quality [10] and improvements of between 1 and 2dB on speech reception threshold(SRT) tests (approximately10–20percentagepoints)[8,10,11].

Whilstpreviousresearchhasdemonstratedthatthe introduc-tionoftechnologiessuchasASCandADROcanprovideimproved speech understanding in noise for paediatric CI users [12,13], limited research on the use of noise reduction or directional microphones in children using cochlear implants is available. Paediatric fittingrates of automatic directionalmicrophonesin hearingaidshavebeenreportedtobeapproximately45%[1]with favourablespeechperceptionoutcomesresultingfromitsuse[14– 16]. To date, there have been no published articles reporting investigationsofautomaticsceneclassification.Giventhis,aclear need exists for evaluation of specific noise technologies in experienced paediatric cochlear implant users to determine if theywillprovidesimilarbenefitstothoseshownforadultCIusers, and whether there are any issues with acceptance of noise reductionofautomationthatshouldbeconsideredininforming clinicalfittingchoices.

1.3. Aims

TheaimofthisstudywastoevaluateexperiencedpaediatricCI usersbenefitstospeechperceptionoutcomesfromthe introduc-tion of new noise reduction technologies implemented in the Nucleus6soundprocessor.Sincechildrenmaybecongenitallyor pre-linguallydeafened,andmayhavedifferenttolerancestonew technologies,itwasnotassumed thattheyshouldshowsimilar levelsofbenefitasthosereportedinstudieswithpost-lingually deafened adultrecipients.Pastresearch, however,hasreported similarbenefitstooutcomesforbothadultsandchildrenfromthe introductionofimprovedstimulationstrategiesand/orfront-end processing. For example, significant improvements in speech understandingwerereportedforbothadultsandchildrenwhen upgrading to the SPEAK stimulation strategy from the MPEAK stimulation strategy [17,18], with no reported problems with acceptance or adaptation to the new technologies. Similarly, significantimprovementsfromtheintroductionofADRO[12,19]

and ASC [20,21]have alsobeen reported in studies withboth adultsandpaediatriccochlearimplantusers.Asecondaryaimof thisstudywastoevaluateacceptanceandadaptationtothenew technologiessuchasautomaticsceneclassificationinagroupof experiencedpaediatricCIusers.

2. Materialsandmethods 2.1. Researchparticipants

Experienced paediatric users of the Nucleus 5 CP810 sound processorwitha CI24REor CI500seriescochlear implantwere recruitedasparticipantsforthisstudy.Selectioncriteriaincluded: childrentobeaged6yearsorolder;haveatleasttwoyears of previousCIexperience;beeitherunilateralorbilateralCIusers; andhaveaminimumscoreof10%onatestofopensetwordsin quiet.Participantswerealsorequiredtobeattendingprimaryor

introductionofanoisereductiontechnology,andallchildrenacceptedthedefaultprogram.These

findingssuggestthatschool-agedchildrenmaybenefitfromupgradingtotheNucleus6soundprocessor

usingthedefaultprogram.

ß2016TheAuthors.PublishedbyElsevierIrelandLtd.ThisisanopenaccessarticleundertheCC

secondaryschool,andtohaveaccesstoappropriateclinicaland habilitationsupport.

Thisstudywasapprovedbyandconductedundertheethical guidance and oversight of the national competent authority (FederaalAgentschapvoorGeneesmiddelenen Gezondheidspro-ducten)inBelgium(BVDE/MVV/2010/10.123);theRoyalVictorian Eye and Ear Hospital Human Research Ethics Committee in Australia (HREC 12/1081H); and the Northern A Health and DisabilityEthicsCommitteeinNewZealand(MEC/12/06/062). 2.2. Soundprocessorprograms

Evaluationswereconductedacrossthreetestingsessions,each ofwhichwasspacedapproximately2weeksapart.Intestsession one, the children’s speech perception was tested using their Nucleus 5 (CP810) sound processor programmed with the participantsownpreferred(N5-preferred)programsettingsused mostfrequentlyduring everyday activities(Table 1). Following completion of testing, subjects werefitted with theNucleus 6 (CP910) soundprocessor using a custom (N6-custom)program thatprovidedequivalentsettingstotheirN5-preferredprogram. Thechildren wore this processorfor everyday usefor approxi-matelytwoweeks,untilthesecondtestsession,at whichtheir speech perception was again evaluated, when using the N6-customprogram.Followingcompletionofthesecondtestsession, adefault N6programwascreated(N6-default),which included ASC,ADRO,SCAN,SNR-NRandWNRtechnologies,whichtogether arereferredcommerciallyastheSmartSoundiQdefaultsettings. ThechildrenthenusedtheN6-defaultprogramforeverydayuse forapproximatelyafurthertwoweek perioduntilthefinaltest session. At the third and final test session, speech perception testingwasagainevaluated.

FortheBelgiansubjects,re-testingwiththeCP810processor and the N5-preferred program was also performed at the last session in quietand noise, and these scores wereused in the followinganalysistoaddressthepotentialissueoflearningeffects. Participants and their carers were also asked by their audiologisttodescribetheirexperiencewiththeNucleus6system

and theirsubjectivepreferencesfollowingthethirdtestsession and outcomes were collected with an open questionnaire. Additionally, participantsand their carersinthe Belgiumclinic were given the choice of retaining their Nucleus 5 sound processor(s),oroptingtopermanentlyupgradetotheNucleus6 soundprocessorwiththeSmartSoundiQtechnologies.

2.3. Studydesign

The study employed a single-subject design, in which each subject served as his or her own control. Speech perception performance withtheN5-preferred, N6-customand N6-default programswasevaluatedforeachsubjectinquiet.Forevaluating benefitsinnoise,speechperceptionperformancewhenusingthe N5-preferredprogramwascomparedtothatusingtheN6-custom programinordertoidentifyanyeffectfromupgradingtothenew soundprocessorbutusingthesameprogram.Comparisonoftest resultswhenusingtheN5-preferredprogramwiththatforthe N6-defaultprogramwasevaluatedtodetermineanybenefitsfromthe introduction of the noise technologies. To control for training effects, subjects were evaluated across three sessions spaced approximately2weeksapart,enablingthechildrentofacilitate acclimationtothedifferentprograms.

2.4. Speechtestinginquietandnoise

All speech tests were conducted in a sound-attenuating audiological booth.Bothspeechandnoise werepresentedfrom asingleloudspeakerlocated1metredirectlyinfrontofthechildas illustratedinFig.1.Theroomwascalibratedtoensurethatthe presentationlevelofthespeechstimuliatthechild’smicrophone wasaccuratelyknown.Allsentenceandwordlistswererandomly selectedfromthelistsavailable.

Monosyllabicwordsinquietwereadministeredat60dBSPL, which represented a conversational speech level for everyday environments. For the Belgian subjects, the NVA (Nederlandse VerenigingvoorAudiologie)wordswereused,withtwolistsof11 words, administered in each condition [22]. For subjects in

Table1

Researchparticipantbiographicdetails.

Num-Clinic Country Gender Ageimplanted Implantuse Implanttype Stimrate Processing Testmode Age Left Right Left Right

01-SAH BE F 6.1 1.6 5.3 4.5 CI512 CI24RE 900 ASC+ADRO Bilateral 02-SAH BE F 7.3 2.3 5.5 5.0 CI512 CI24RE 900 ASC+ADRO Bilateral 03-SAH BE M 12.3 5.0 – 7.3 CI24RE HA 900 ASC+ADRO Unilateral 04-SAH BE F 8.4 3.2 6.7 5.2 CI24RE CI24RE 900 ASC+ADRO Bilateral 05-SAH BE F 7.8 7.3 6.1 1.7 CI24RE CI24RE 900 ASC+ADRO Bilateral 06-SAH BE F 9.3 2.3 4.6 7.0 CI512 CI24RE 900 ASC+ADRO Bilateral 07-SAH BE F 8.7 6.7 7.6 2.0 CI24RE CI24RE 2400 ASC+ADRO Bilateral 08-SAH BE F 6.0 – 4.6 1.4 HA CI24RE 900 ASC+ADRO Unilateral 09-SAH BE F 8.0 6.0 7.3 2.0 CI24RE CI24RE 900 ASC+ADRO Bilateral 10-HSC AU F 9.3 4.3 8.4 5.0 CI24RE CI24RE 900 ADRO Bilateral 11-HSC AU M 10.5 7.6 3.8 6.7 CI24RE CI24RE 720 ADRO Bilateral 12-HSC AU F 8.3 6.0 6.5 2.3 CI24RE CI24RE 720 ADRO Bilateral 13-HSC AU M 11.1 3.5 5.3 7.6 CI24RE CI24RE 900 ADRO Bilateral 14-HSC AU M 7.9 2.3 1.7 6.2 CI512 CI24RE 900 ADRO Bilateral 15-HSC AU M 12.3 11.2 4.4 7.9 CI24RE CI24RE 900 ADRO Bilateral 16-HSC AU F 6.1 2.6 4.1 3.5 CI512 CI24RE 900 ADRO Bilateral 17-MCIC AU M 8.4 6.8 6.3 2.1 CI24RE CI24RE 900 ASC+ADRO Bilateral 18-MCIC AU F 6.5 5.7 4.7 1.8 CI24RE CI24RE 900 ADRO Bilateral 19-MCIC AU F 7.5 7.0 6.4 1.1 CI24RE CI24RE 900 ADRO Bilateral 20-MCIC AU F 11.2 4.9 7.1 6.3 CI24RE CI24RE 900 ASC+ADRO Bilateral 21-MCIC AU F 9.2 5.9 – 3.3 CI24RE HA 900 ASC+ADRO Bimodal 22-MCIC AU M 8.8 5.9 7.6 2.9 CI24RE CI24RE 900 ASC+ADRO Bilateral 23-THH NZ F 10.4 – 2.7 7.7 HA CI512 900 ADRO Unilateral 24-THH NZ F 10.8 – 7.6 3.2 – CI24RE 900 ASC+ADRO Unilateral 25-THH NZ F 15.0 – 3.4 11.6 – CI24RE 900 ASC+ADRO Unilateral

Australia&NewZealand, testingwasconductedusingtheCNC (Consonant NucleusConsonant) words, with a singlelist of 50 wordsadministeredineachcondition[10,23].

Giventheageofthesubjects,testinginnoisewasconducted usingfixed-leveltesting.InBelgium,themonosyllabicwordswere presentedat65dBSPLinspeech-weightednoise(SWN)atalevel whereparticipantsscoredbetween40%and70%intheirfirstvisit. For eight participants this was a level of 65dB SPL, and for participantCTC07 itwasalevelof60dBSPL.Themonosyllabic wordtest wasusedastherewereno suitableFlemishlanguage sentencelists forchildrenavailableat thetime ofthestudy.In Australia &New Zealand clinics CUNY (City University of New York)sentences werepresentedat65dBSPLin50dBSPLSWN noise(HSC,THH)or55dBSWNnoise(MCIC).

3. Results

3.1. Researchparticipantinformation

A total of 25 children who met the selection criteria were recruited:ninefromtheEuropeanInstituteforORL-HNSinAntwerp, Belgium(SAH);sevenfromtheHearandSayCentreinBrisbane, Australia (HSC); six from the Cochlear Implant Centre, Royal VictorianEye and Ear Hospital in Melbourne, Australia (MCIC); andthreefromTheHearingHouseinAuckland,NewZealand(THH). BiographicalinformationontheparticipantsisshowninTable1. Eighteenparticipantswere femaleandsevenweremale. Partici-pants’agesrangedbetween6and15years.Theaveragedurationof implantusewas6.1years(rangingfrom2.3yearsto11.2years).Of the25participants,19werebilateralCIusers.Inthesecases,both processorsusedthesamestimulusrateandthesameprocessing technologies,andbothprocessorswereupgradedtogetherduring testsessions.OfthesixunilateralCIusers,fourwerebimodalusers, havingahearingaidinthecontralateralear.Whenprocessorswere wornathome,thehearingaidwasenabledandusedtogetherwith theCI.However,duringtestsessions,threeoftheparticipantswere tested unilaterally using their CI only, while one participant, 21-MCIC,wastestedbimodallyusingboththeirCIandtheirhearing aid.TwoparticipantswereunilateralCIrecipientswhodidnotuse any assistive hearing device in their contralateral ear. These participantsweretestedunilaterallyusingtheirCIonly.

3.2. Speechperceptioninquiet

Individualscoresofeachofthesubjectsforthethreeprograms, togetherwithgroupmeanresultsforthemonosyllabicwordtestin quiet are shown in Fig. 2. Given that there were no obvious

differencesintheperformancemeansandrangesfoundforthe subjectstestedinquietusingthetwodifferentlanguagetests,the dataforallsubjectswascombinedforstatisticalanalysis.A one-way repeated measuresanalysis-of-variance(ANOVA) on ranks wasusedtodetermineiftherewasanysignificantdifferencein outcomesacrossthethreeprograms.Nostatisticaldifferencewas foundinoutcomesforanyofthethreeprogramsonthetestsof speechperceptioninquiet.

3.3. Speechperceptioninnoise

Inthecaseoftestingforbenefitstospeechperceptioninnoise, duetotheuseofmonosyllabicwordsinnoisetestfortheBelgian subjects,incontrasttoasentenceinnoisetest forthe English-speakingsubjects,theresultsforspeechperceptioninnoisewere analysed separately for the two language groups. Individual subjectscoresandgroupmeandataforthenineBelgiansubjects on the test of monosyllabic wordsin noise is shown in Fig.3. Although the speech weighted noise presentation level was selectedtoresultinparticipantsscoresfallingbetween40%and 70%,thegroupaveragewas33%.Thiswaslowerthanexpected,and thoughtto bedue totest variability. Paired t-tests showedno significant difference between N5-preferred and N6-custom programs. However, paired t-tests showed a significant 16.7 percentagepointimprovementingroupmeanscoresforthe N6-default (50.0%) as compared to theN5-preferred (33.3%) (t=9, p<0.01)condition.

Individualsubjectscoresandgroupmeansentencedataforthe English-speaking subjectsfrom Australia and New Zealand are shown inFig.4.Paired t-testsshowedno significantdifference between N5-preferred and N6-custom programs. However a significant9.41percentagepointmeanimprovementinsentences scores was shown for the N6-default condition (71.0%) as compared to results in the N5-preferred condition (61.6%) (t=16,p<0.05).

Subjectivepreferencequestionnaireresultsindicatedthat all recipients were able to easily adapt to use of the N6-default program,andnospecificproblemswereidentifiedinsoundquality or listening abilities. After thefinal session providing approxi-matelyfourweeksoftake-homeuse,allnineparticipantsfromthe Belgium clinicchose to upgradepermanentlyto theNucleus6 soundprocessorswiththedefaultSmartSoundiQprogram.From all clinics, the fitting and upgrading process of paediatric participantsprogressedsmoothlyanddidnotposeanyproblems. 4. Discussion

Theaimsofthisstudyweretoevaluatewhetherexperienced paediatriccochlearimplantuserswouldshowsimilarbenefitsin speech perception from use of noise reduction technologies implementedintheNucleus6soundprocessortothosepreviously shown withadult cochlear implantrecipients, and secondly to identify any issues with user acceptance to the upgrade. This information on comparative performance of theNucleus6 and Nucleus5 cochlear implantsystems,togetherwithinformation gainedonsatisfactionwithandacceptanceofthenoisereduction technologieswouldbeimportantforrecipientsandtheirfamilies consideringupgradingtotheNucleus6technology.

Resultsofspeechperceptiontestsinquietshowedcomparable performance between the two systems, and across the three programconditionstested.Thiswasasexpected,giventhatsimilar programswereimplementedintheN5-preferredandN6-custom conditions,andthatSmartSoundiQnoisereductiontechnologies implementedin theN6-defaultcondition werenotdesigned to targetperformanceinquietconditions.Indeed,theseresultsare consistentwiththeNucleus6findingsreportedforexperienced

adultcochlearimplantusersevaluatedwithbothNucleus5and Nucleus6programs[7,24].

In contrast, results for speech perception in noise were significantlyimprovedforallsubjectswhenusingtheNucleus6 processorwiththedefaultprogramincludingtheSmartSoundiQ noise reduction technologies, as compared withtheir previous Nucleus 5 processor and program (16.7 percentage points for Belgiansubjects,and9.7percentagepointsforEnglishspeaking). This difference appears to be due to the implementation of backgroundnoisereduction(SNR-NR)ontheNucleus6device,as theotherintroducedtechnologies(SCANandwindnoisereduction (WNR))arenotexpectedtoprovideanychangeinanS0N0test. Similaroutcomesforimprovedspeechperceptioninnoisehave beenreportedwithadultscochlearimplantusers,whoshoweda 1.2–1.7dBimprovement inSRT fora similartest configuration, equivalent to approximately a 10–20% increase in speech perceptionscoresforFlemishandEnglishspeakingadultsubjects

[7,24]. Similarly to previous Flemish and English adult studies

[7,24], subjectselectiondidnot influenceunilateralor bilateral capacities,astheaimofthesestudieswastoassessthebenefitsfor thegeneral upgradepopulation. AlthoughbilateralpaediatricCI usersabsoluteperformance levelhasbeen foundtobeslightly improvedcomparedtounilateralusers[25],additionalbenefitsfor

thenewlyincludedtechnologies,andinparticularnoisereduction, are expected to provide similar improvements for both user groups.Furtherstudiesshouldhoweverinvestigateperformance and acceptance of these new technologies between unilateral, bilateralandarangeofbimodalusergroups.

Resultsfor subjectivepreferenceindicatedthatallrecipients wereabletoeasilyadapttouseoftheN6-defaultprogram,andno problemswereidentifiedinsoundquality.Thiswasthecasefor bilateralCIusers,andbimodalandunilateralCIusersalike.Atthe endofthestudy,afterapproximatelyfourweeksoftake-homeuse oftheNucleus6soundprocessor,allparticipantsfromtheBelgium clinic(withinputfromtheircarers)chosetoupgradepermanently tothissoundprocessorwiththedefaultprocessing.Forsubjectsin AustraliaandNewZealand,Nucleus6systemswereprovidedona loanbasis,withtheunderstandingthatthesedeviceswouldonly beusedduringthetrialasrequiredbythelocalethicsapproval. 4.1. Directionalmicrophonesandautomaticsceneclassification

Previous generations of Nucleus sound processors have incorporatedthecapabilitytoselectivelyattenuatesoundsbased on their direction of arrival through the use of directional microphones. This capability required that the user manually switch between several processor programs and microphone configurationstoadapttodifferentsignalinnoiseenvironments.

Fig.2.PercentcorrectscoresonmonosyllabicwordtestinquietforN5-preferred,N6-customandN6-defaultprogramconditions.Groupmeanscoresareshownontheright forthethreeprogramconditions,witherrorbarsshowingthestandarderrorofthemean(SEM).

Fig.3.PercentcorrectscoresonmonosyllabicwordsinSWNnoiseforN5-default, N6-customandN6-defaultprograms.Groupmeanscoresareshownontheright, witherrorbarsshowingSEM.Forsubject04-SAH,nodatawasavailableforthe N6-customcondition,soresultsfortheotherprogramswereremovedfromthegroup averageandSEMcalculation.

Fig.4.PercentcorrectscoresforCUNYsentencesinSWNfortheN5-preferred program,theN6-customprogramandtheN6-defaultprogram.Groupmeanscores areshownontheright,witherrorbarsshowingSEM.

Inadults,manualswitchingofprogramsaccordingtothelistening environment has been reported to be as low as only 10% of recipients[26].Whilethemanualselectionapproachisfeasiblefor adultsandolderchildrenwhoarecompetentinthemanagement oftheirdevice,itisfarlessapplicableandsuitableforinfantsand youngerchildrenwhoaredependentuponcarerstochangetheir programsandtojudgewhetherthecorrectprogramshavebeen selectedfordifferentenvironments.Sincedirectionalmicrophones inhearingaidscanattenuatesoundsfromthesidesandback,itis thoughtthat theymayreduceincidentallearning opportunities

[14,27,28].Duetobothmanualswitchingpracticalitiesandnotto limit incidental learning opportunities, a moderate directional microphone tomimic the natural ears directional processing is commonlyselectedforpaediatricCIusers.Inthecurrentstudy,all childrenwerefittedwithsuchamoderatelydirectionalmicrophone program(Standard)priortojoiningthestudy.Toaddressthisissue, Nucleus6hasthecapability(viaSCAN)toautomaticallyadjustand control microphone directionality via scene analysis, thereby requiring no manualadjustment ofthe soundprocessor by the user.Thistechnologyselectsamoderatedirectionalmicrophonefor useinquiet,andautomaticallychangestoastronglydirectional microphoneinnoisyenvironmentstoprovidethebestopportunity ofunderstandingspeechinpoorsignal-to-noiseratios.

Previousresearchhasclearlydemonstratedthebenefitofgood signal-to-noiseratiosforspeechunderstandinginchildren.Studies withnormal-hearingchildrenhavereportedthatahigh signal-to-noiseratio(SNR),typicallyintherangeof15dB,isrequiredfor good speech understanding. Studies with CI recipients have reported that speech understanding is reduced significantly in lowerSNRs [3,29], yet many environments suchas classrooms havebeenmeasuredataround0dBSNR[14].AstheSNRdegrades toapointwherespeechunderstandingisimpacted,thecapacityto automatically engage directional microphones to compensate wouldbeadistinctclinicaladvantage.Conversely,whenaquiet environment is detected, automatic reduction in thedegree of microphonedirectionalitywouldbemoreappropriateforlowlevel listening.Unfortunately,inthisstudy,theeffectsofmicrophone directionalitywerenot directlyevaluatedduetotheco-located speech and noise speaker configuration used during testing. Furthernoisetestingwithspatiallyseparatedspeaker configura-tionsandarangeofnoisetypesshouldbeconsideredforfuture studies. One final consideration of the automatic functioning implementedinSCANisitsadaptivenatureinselectingdifferent directionalmicrophoneoptions.Itisimportanttonotethatwith Nucleus6,SCANappliesthesetransitionssmoothlytoavoidan intrusiveordisruptiveimpactonthelistener.Duringthisstudy, none of the children reported that the automatic adjustments madebySCAN ontheNucleus6soundprocessorwereobvious and/ordistracting,whichwasalsothecasereportedinaprevious study of the Nucleus 6 sound processor in experienced adult cochlearimplantrecipients[7].

4.2. Noisereductiontechnology

Backgroundnoisereductiontechnologiesarearelativelynew featurein CIsandtodate,little clinicalinformation isavailable regardingtheirusewithpaediatricrecipients.Nucleus6SNR-NRis designedtoretainmuchofthetransientinformationinsignalslike speech, but to attenuate the more constant steady-state type signals in background noise which predominantly masks the speech signal and delivers only redundant information. This technologyisoninalllisteningscenesandadaptseachfrequency channelconstantlytothechangingnoiselevel.Inapreviousstudy testing a different background noise reduction technology in children,noperformanceimprovementwasreportedfortestsin quiet,butasignificantimprovementwasfoundfortestsofspeech

perception in constant background noise [30]. In that study, a rangeofmapchangeswasalsoperformedduringnoisereduction fitting,includingchangestothemaximumandminimumstimulus levels [30]. In the current study, no changes in mapping were performedorrequired,astheSNR-NRwassimplyenabledinthe fitting software. The absence of any additional clinical fitting requirements to enable SNR-NR is beneficial, as trialling of numeroussettingsrequiringfeedbackfromchildrenateachstage, increasesfittingtimeandmaynotbeappropriateorfeasibleinthe caseofinfantsoryoungerchildren.

4.3. UseofNucleus6forpaediatricfittings

Theresultsofthisstudyshowedthatuseofnoisereduction technologies as implemented with Nucleus SmartSound iQ providedbenefitstospeechperceptioninbackgroundnoisefor this group of paediatric users, without any decrement to performance in quiet. Furthermore, all users, being bilateral, bimodalor unilateralwereabletoupgradeeasilyanddidnot experienceanynegativelisteningorsoundqualityproblems.The datasupportstheconclusionthatuseofSCANandbackground noise reduction is helpful forchildren as well as adults, and shouldthereforebeconsideredforallpaediatricCIfittings.Many ofthesubjectsinthisstudyhadhadsomelisteningexperience with SmartSound settings (including ASC and ADRO) prior to upgradingtoNucleus6,howevernonehadbeenexposedtothe comprehensiverangeofSmartSoundiQoptionsincludingSCAN, SNR-NRandWNR.Asreported,thesewerewelltoleratedbyall childrenincludingsomewithlengthyperiodsofdeviceuseprior to the upgrade. The Nucleus 6 sound processor offers four programslotssoinadditiontousingthedefaultSmartSoundiQ program, a custom programcan be providedwhichmay bea modified SmartSound iQ program or one with equivalent programsettingstothoseonalegacyprocessortoaidacclimation duringupgrade.

4.4. Studylimitations

Thewithin-subjectdesignofthisstudywasselectedtomitigate some of the well-known issues with testing young paediatric recipients(likelimitedattentionspan,inabilitytoreportonsound quality,etc.).In addition,children wererecruitedfrommultiple clinicsandindifferentcountries,toensurethatthe recommenda-tions on benefitsfromuseof newnoise reductiontechnologies wouldbegeneralisabletothewiderclinicalpopulation.However, thiscreatedadownsideofthisdesignintheneedtocontrolforthe differentlanguagetestsused.Whilethemonosyllabic wordtest resultscouldbecollapsedacrosslanguageforanalysis(duetothe same wordstructure and a similarspeech perception outcome ranges),thiswasnotpossibleforthespeechperceptioninnoise results,duetotheunavailabilityofanappropriatesentencetestin noiseforchildreninBelgium.

Afurtherissuetobeconsideredinapplicationoftheseresultsis thepotentialforlearningduringanyevaluationinvolvingchildren. Thestudydesignrequiredthatonlythreesessionswerescheduled, and test sessions were kept short, aimed at maintaining high attention throughout testing. To mitigate the potential for a learning effect, experienced subjects were selected who had performed the same or similar tests previously in the clinical setting. A simple, co-located speaker/noise experimental setup was used, and a limited battery of tests was administered to maximiseattentionspanthroughoutthetestsessions.Finally,the words and sentences used were randomly selected, and no material was repeated acrossthe three evaluations. Testingin morecomplexspatiallyseparateconditionsshouldbeconsidered infuture studiestogain furtherevidenceofthebenefitofdual

microphonesand automatic adjustment of these for paediatric recipients.

5. Conclusion

Experiencedpaediatriccochlearimplantusersshowed signifi-cantimprovementsinspeechperceptioninnoisefromtheuseof noisereductiontechnologiesimplementedintheNucleus6sound processor. Subjectseasily adapted tointroduction of the noise technologieswithoutanyreportedimpactonspeechperceptionin quiet or in noise. These results provide preliminary support regardingthesuitabilityofuseofsuchtechnologiesasSCANand SNR-NR in the paediatric population. More broadly, this data suggeststhatbothautomaticsceneclassificationandbackground noise reduction technologies are suitable and beneficial for experiencedpaediatric CI users as wellas for adults. Based on theseresults,useofthesetechnologiesshouldbeconsideredfor paediatricCIfittings.

Conflictofinterests

Thisstudy wassponsored by CochlearLimited. The authors withaffiliationswithCochlearLimitedareemployeesofCochlear Limited, the manufacturer of the technology described in the article.

Acknowledgements

Theauthorsaregratefulfortheparticipationoftheresearch participantsandtheirfamilies/carersinthestudy.We acknowl-edgethefinancialsupportof theHEARing CRC,establishedand supported under the Business Cooperative Research Centres ProgrammeoftheAustralianGovernment,aswellasthesupport oftheparticipatingclinicalcentresandtheirstaff.

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