Otology Korean J Otorhinolaryngol-Head Neck Surg 2018;61(6): / pissn / eissn Cl

Otology Korean J Otorhinolaryngol-Head Neck Surg 2018;61(6):287-94 / pissn 2092-5859 / eissn 2092-6529 https://doi.org/10.3342/kjorl-hns.2017.00668 Clinical Usefulness of Speech Mapping for Fitting of Hearing Aids So Yean Kim, Jin Su Park, and Min-Beom Kim Department of Otorhinolaryngology-Head and Neck Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea 보청기의적합과정에서스피치매핑의임상적유용성 김소연 박진수 김민범 성균관대학교의과대학강북삼성병원이비인후과학교실 Received July 20, 2017 Revised August 25, 2017 Accepted August 28, 2017 Address for correspondence Min-Beom Kim, MD Department of Otorhinolaryngology- Head and Neck Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul 03181, Korea Tel +82-2-2001-2264 Fax +82-2-2001-2273 E-mail minbeom.kim@gmail.com Background and ObjectivesZZThe aim of this study was to evaluate the usefulness of speech mapping based on real ear measurement for routine hearing aid fitting and to compare functional gains for evaluating subjective satisfaction of hearing aid users. Subjects and MethodZZTwenty two participants with bilateral symmetric (<10 db HL difference) sensorineural hearing loss were enrolled in this study. All participants were fitted unilateral hearing aids with speech mapping using the National Acoustic Laboratories-Nonlinear 2 formula. After the initial fitting, patients were followed with the 2nd and 3rd fitting at two weeks and six weeks, respectively, and measured for aided pure tone average (PTA), aided speech discrimination score (SDS), the difference between target gain and real ear insertion gain (REIG) using speech mapping and subjective satisfaction via Korean Adaptation of the International Outcome Inventory for Hearing Aids (K-IOI-HA) questionnaire before further fitting was performed. We analyzed correlation of each parameter at 2nd and 3rd fitting with the K-IOI-HA score. ResultsZZEvery sequential aided PTA and SDS at 2nd fitting and 3rd fitting were significantly improved after repeated hearing aid fitting (all p<0.01). In the correlation analysis between K-IOI-HA and each parameter, the aided PTA and aided SDS did not show significant correlations with subjective satisfaction from the 2nd and 3rd fittings. But the difference between the target gain and REIG in speech mapping showed significant negative correlations with the satisfaction scores at various speech level (r=-0.609 to -0.709, all p<0.01). ConclusionZZSpeech mapping using real ear measurement was useful to expect subjective satisfaction of hearing aid users and it would be a valuable tool for fine tuning to achieve individual preferences. Korean J Otorhinolaryngol-Head Neck Surg 2018;61(6):287-94 Key WordsZZAuditory threshold ㆍ Hearing aids ㆍ Hearing loss ㆍ Questionnaire. 서 론 보청기의적합 (hearing aid fitting) 은환자청력손실의특 성을고려하여가장적절한형태의보청기를선택한후음향 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 이득과출력음압을결정하는과정이다. 보청기를처방한후에는보청기증폭기능을통한음향학적이득을평가하기위한보청기의기계적검증 (verification) 이필요하며환자가보청기를착용함으로써일상생활에얼마나도움을받고만족하는지를확인하는보청기의기능적확인 (validation) 도필요하다. 보청기를착용한후환자가얼마나말소리를정확하고편안하게잘알아들을수있는지를측정하고환자의귀 Copyright 2018 Korean Society of Otorhinolaryngology-Head and Neck Surgery 287

Korean J Otorhinolaryngol-Head Neck Surg 2018;61(6):287-94 에알맞게조절해주는과정은필수적으로중요한일이다. 환자의청력역치에근거한처방법으로보청기를처방한후에는목표만큼이득을전달하는지기계적검증을통해보청기자체의기능을확인해야한다. 이를측정하는방법은크게세가지로방음실내의스피커를통해음이방사되는음장 (sound field) 에서보청기를착용하지않은상태와착용한상태에서주관적인청각음향학적측정을하여기능적이득 (functional gain) 을계산하는음장측정 (sound field measurement), 실제외이도내에서보청기를사용한경우와사용하지않은경우의청력역치를객관적으로측정하여실이삽입이득 (real ear insertion gain, REIG) 을계산하는실이측정 (real ear measurement), 2 cc 접합기를사용하여보청기의음향학적이득을객관적으로평가하는접합기반응 (coupler response) 등이있다. 1) 실이측정은실제환자의외이도내부의고막가까이에실리콘재질의 probe microphone관을삽입하여보청기를착용하지않은상태와착용한상태에서각각외이도내부의음향학적특성의 db sound pressure level을측정하는방법이다. 이방법은객관적인검사로써주관적으로측정되는기능적이득과달리환자가응답하지않아도되므로어린유소아에서도시행할수있으며검사시간이적게소요되는장점이있다. 여러가지입력음과음압에있어각주파수에서보청기에의해증폭된음압이보청기를착용하지않았을때의실이공명반응 (real ear unaided response, REUR) 에비해서얼마나증가하였는지실이삽입이득 (REIG) 을측정하여목표이득 (target gain) 과얼마나차이가나는지를구하여보청기의이득을조절할수있다. 2) Speech mapping 은실이측정을기반으로한보청기의기계적검증방법으로검사를위해서순음신호 (pure tone signal) 를사용하지않고일상생활에서접하는대화나음악, 말소리등을활용하는장점이있다. 순음신호의경우최근디지털보청기의잡음제거 (noise reduction) 기능, 음향되울림제거 (acoustic feedback cancellation) 기능에의해잡음이나되울림으로받아들여져보청기의적절한성능의평가에어려움이있을수있으나말소리를활용하는경우이러한오류를피할수있다. 또한 speech mapping의결과가청력도 (audiogram) 의형태로바로보여지기때문에환자의이해를도와순응도를높이는데도움을줄수있다. 3) 저자들은보청기의적합과정에있어오래전부터통상적으로사용되고있는음장청력검사 (sound field audiometry) 와 speech mapping을비교하고, 어떠한방법이환자의주관적만족도를예측하는데있어우수한지확인해보고자하였다. 대상및방법 대상 2013년 5~7월강북삼성병원에내원하여보청기를착용하게된환자를대상으로후향적분석을진행하였다. 대상기준은 40~70 db의청력역치를보이는중등도및중등고도난청이면서양측청력역치의차이가 10 db 미만인양측대칭성감각신경성난청환자들을대상으로하였다. 이중소아, 전음성난청, 추적소실, 뇌혈관질환이나인지장애등신경학적기저질환을가진환자들은제외하여총 22명의대상자를선정하였다. 환자군의평균나이는 69.5세, 성별은남자 7명, 여자 15명, 보청기착용방향은우측 9명, 좌측 13명이었다. 검사방법각대상자에서처음보청기를맞추기위해외래를내원하였을때 (1차 fitting) 보청기미착용시의음장순음청력검사 [unaided pure tone average(pta)] 와어음청력검사 [unaided speech discrimination score(sds)] 를시행하였다. 모든대상자는 Aurical FreeFit R (Otometrics, Taastrup, Denmark) 을이용하여 National Acoustic Laboratories-Nonlinear 2 formula를통해일측성의보청기적합과 speech mapping을시행하였다. Speech mapping에서는 250, 500, 1000, 2000, 4000, 8000 Hz의 6개각주파수에서목표이득 (target gain) 과실이삽입이득 (REIG) 의차이를구하여더한총합을분석하였다. 대상자들은 1차적합으로부터 2주후 (2차적합 ) 와 6주후 (3차적합 ) 경과시외래로내원하여보청기착용시의음장순음역치 (aided PTA) 와어음명료도 (aided SDS) 를측정하였으며, speech mapping에서는 250~8000 Hz의각주파수에서목표이득과실이삽입이득 (REIG) 의차이를구하여더한총합을분석하였다. 보청기로증폭된소리가환자에게얼마나주관적인만족감을주는지를확인하기위한기능적확인으로서 Korean Adaptation of the International Outcome Inventory for Hearing Aids(K-IOI-HA) 설문지를시행하였다. 우리는 2차적합과 3차적합시시행한음장청력검사및 speech mapping의여러측정값과 K-IOI-HA 설문지를통한주관적만족감과의상관관계를분석하였다 (Fig. 1). Sound field audiometry 음장에서의주관적역치 (subjective threshold) 측정은이중방음벽으로구성된방음실안에서 Madsen Astera 2 audiometer R (Otometrics) 와이에장착되어있는 2개의 external free-field amplifier speaker를사용하였다. 환자와스피커 288

Speech Mapping Kim SY, et al. 22 Subjects with unilateral hearing aid initial visit with 1st fitting Fitting algorithm with NAL-NL2 formula sound field unaided PTA, unaided SDS speech mapping 2nd fitting with fine tuning (2 weeks later) Sound field aided PTA, aided SDS speech mapping K-IOI-HA questionnaire 3rd fitting with fine tuning (6 weeks later) Sound field aided PTA, aided SDS speech mapping K-IOI-HA questionnaire Fig. 1. Shown is the design of the study. NAL-NL2: National Acoustic Laboratories- nonlinear 2, PTA: pure tone average, SDS: speech discrimination score, K-IOI-HA: Korean Adaptation of the International Outcome Inventory for Hearing Aids. 의거리를 1 m로하고각스피커는환자의양측 45 방위각 (azimuth) 에위치시킨후변조순음 (warble tone) 으로측정하였다. 검사주파수는 250, 500, 1000, 2000, 4000, 8000 Hz로하여측정하였다. 보청기착용시순음청력역치 (aided PTA), 어음명료도 (aided SDS), 보청기착용에따른기능적이득 (unaided PTA-aided PTA), 보청기착용에따른어음명료도의호전정도 (aided SDS-unaided SDS) 등총네가지지표를 2차적합과 3차적합시에각각측정하였다. Speech mapping 실이측정을통한객관적인보청기의기계적검증은 Aurical FreeFit R system을사용하였다. 이시스템은환자의양이와목에거치하는외부장치 (wireless speechlink 100 binaural neckset) 와프로그램 (visible speech software) 으로구성되어있으며, 양이에거치하는 2개의 module은 reference microphone과실리콘재질의유연한 probe microphone으로이루어져있다. 주변잡음이통제된음장에서환자는정면을바라보고이마에서약 1 m 떨어진거리에음장스피커를위치시켰다. 검사를시행하기전 probe microphone 을 reference microphone에연결시켜보정 (calibration) 하였으며, 이경을통해환자의외이도상태와길이를파악한뒤 probe microphone이고막에서 2~5 mm 떨어진곳에위치할수있도록환자의외이도에삽입하였다. 우리는 speech mapping system 에보청기적합소프트웨어인 NOAH link(himsa, Copenhagen, Denmark) 를연결하여환자의청력도와목표이득값을반영한보청기의조절이실시간으로이루어지도록하였다. Microphone의신호대역은목에거치하는외부장치의무선링크를통해컴퓨터에전달되어환자의외이도내에서의신 Hearing level (db) db HL REAR -10 0 10 20 30 40 50 60 70 80 90 100 110 120 125 250 500 1 k 2 k 4 k 8 k Hz Frequency in Hz Fig. 2. Verification of unilateral hearing aid on 3 input levels for speech stimuli by the Aurical FreeFit, soft speech level (55 db HL), comfortable speech level (65 db HL) and loud speech level (75 db HL). Figure shows example of speech mapping in comfortable speech level (65 db HL). Shadow area shows spectrum of sounds in the ear canal, solid curve shows real ear aided gain and dotted curve shows real ear unaided gain+target gain. REAR: real ear aided response. 호스펙트럼을적합과정동안실시간으로조절자와환자에 게보여주었다. 실제말소리는작은소리단계 (soft speech level, 55 db HL), 중간소리단계 (comfortable speech level, 65 db HL), 큰소리단계 (loud speech level, 75 db HL) 로구 분해제시하여보청기의이득을측정하였다. 참조한그림 (Fig. 2) 에서점선은보청기착용시프로그램으로처방된목 표이득에서실이공명이득 (real ear unaided gain) 을합한역치 www.kjorl.org 289

Korean J Otorhinolaryngol-Head Neck Surg 2018;61(6):287-94 값이며실선은보청기를착용후실이증폭이득 (real ear aided gain) 수치로점선과실선의차이는목표이득과실이삽입이득 (REIG) 의차이를나타낸다. 250, 500, 1000, 2000, 4000, 8000 Hz의 6개각주파수에서목표이득과실이삽입이득 (REIG) 의차이를구하여총합을구하였다. K-IOI-HA Questionnaire 보청기효과의주관적평가를위해널리사용되고있는설문지중의하나인 International Outcome Inventory for Hearing Aids(IOI-HA) 의한국어번역판을사용하였다. 총 7개의질문항목으로구성되어있고, 각각의항목은보청기착용후일상생활에서의보청기사용시간 (daily use), 이익 (benefit), 보청기사용에따른활동 (residual activity), 만족도 (satisfaction), 남아있는활동제한 (residual participation restrictions), 타인에끼치는영향 (impact on others), 삶의질 (quality of life) 등으로구성되어각각다른결과영역을대변하고있다. 각질문항목은 5개의보기를선택할수있도록 구성되어있고, 가장나쁜결과를의미하는보기를가장좌측에배치하여 1점으로점수화하고, 우측으로갈수록점점긍정적인의미의보기를설정하고 1점씩더하여가장우측의보기항목은 5점으로정하였다. 각질문항목의점수는 1점부터 5점까지, 총점은최소 5점부터최대 35점까지표시할수있다 (Fig. 3). 4) 분석방법통계처리는 Windows용 SPSS version 18.0(SPSS Inc., Chicago, IL, USA), STATA version 14.0(STATA Corp., LP, TX, USA) 프로그램을이용하여분석하였으며 p value가 0.05 미만인경우를통계학적으로유의한것으로정의하였다. 통계분석에앞서모집단에대한정규성검정을시행하였으며, 정규분포를위배하지않아모수적검정법 (parametric statistical test) 을사용하였다. 보청기적합이거듭될수록음장청력검사에서의청력이득에대한경향성은 repeated measures ANOVA를사용하였으며, speech mapping에서의청력 1. 지난 2주간현재가지고있는보청기를얼마나자주사용했는지생각해보십시오. 하루에평균몇시간이나보청기를사용하십니까? 사용하지않음 1시간미만 1~4시간 4~8시간 8시간이상 (2~3) 현재가지고있는보청기를사용하기전에, 소리를더잘듣기원했던상황을생각해보십시오. 2. 지난 2주간이런상황들에서보청기를사용하여얼마나도움을받았습니까? 전혀도움이 조금 보통이다 많은 아주많은 되지않았다 도움이되었다 도움이되었다 도움이되었다 3. 현재의보청기를사용하고도, 같은상황에서얼마나여전히불편하십니까? 아주많이 많이 보통이다 조금 전혀 불편하다 불편하다 불편하다 불편하지않다 4. 모든점을고려할때, 현재사용하는보청기가그로인한불편함을감수할만한가치가있습니까? 전혀그렇지않다 조금그렇다 보통이다 많이그렇다 아주많이그렇다 5. 지난 2 주간현재의보청기를사용하고도, 청력으로인한불편함이귀하가할수있는일에얼마나지장을주었습니까? 아주많이그렇다 많이그렇다 보통이다 조금그렇다 전혀그렇지않다 6. 지난 2 주간현재의보청기를사용하고도, 귀하의청력이상이다른사람들에게얼마나불편함을주었다고생각하십니까? 아주많이그렇다 많이그렇다 보통이다 조금그렇다 전혀그렇지않다 7. 모든점을고려할때, 현재의보청기를사용하여귀하의삶의질이얼마나즐거워졌습니까? 악화되었다 변화없다 조금 많이 아주많이 즐거워졌다 즐거워졌다 즐거워졌다 Fig. 3. Korean version of International Outcome Inventory for Hearing Aids questionnaire. 290

Speech Mapping Kim SY, et al. 이득에대한경향성은대응표본 t 검정 (paired t-test of difference) 을사용하여대표값으로평균과표준편차를제시하였다. 음장청력검사및 speech mapping 검사에서의각지표와 K-IOI-HA score와의연관성은피어슨상관분석 (Pearson s correlation analysis) 과선형회귀분석 (linear regression analysis) 을이용하였다. 15.0 db이었으며 3차적합에서목표이득과 REIG의차이는작은소리단계에서 16.8 db, 중간소리단계에서 12.5 db, 큰소리단계에서 11.2 db로나타나 3차적합시에는 2차적합시에비해목표이득과 REIG의차이가감소하는경향을보였다. 하지만대응표본 t 검정을이용한통계분석에서는중간소리단계에서만유의한차이를보였다 (p=0.014)(table 1). 결과 음장청력검사 (Sound field audiometry) 음장에서의청력역치는 1차적합에서보청기미착용시 (unaided PTA) 평균 55.0 db이었으며 2차적합에서보청기착용시 (aided PTA) 37.4 db, 3차적합에서보청기착용시 (aided PTA) 31.4 db로점차호전되는양상을보였다 (Fig. 4A). 음장에서의어음명료도의경우에도 1차적합시보청기미착용시 (unaided SDS) 평균 78.5%, 2차적합에서보청기착용시 (aided SDS) 91.0%, 3차적합에서보청기착용시 (aided SDS) 94.0% 로호전을보였으며모두통계적으로유의한차이를보였다 (Fig. 4B). Speech mapping 2차적합에서목표이득과 REIG의차이는작은소리단계에서 20.0 db, 중간소리단계에서 18.0 db, 큰소리단계에서 K-IOI-HA score와각지표와의상관분석 Speech mapping에서의목표이득과 REIG의차이를비롯하여음장청력검사를이용한보청기착용시순음청력역치 (aided PTA), 어음명료도 (aided SDS), 보청기착용에따른 functional gain(unaided PTA-aided PTA), 보청기착용에따른어음명료도의호전정도 (aided SDS-unaided SDS) 총다섯가지지표와주관적만족감을나타내는 K-IOI-HA questionnaire score 사이에의상관분석과회귀분석을시행하였다. 2차적합에서는 speech mapping의작은소리단계, 중간소리단계, 큰소리단계에서의목표이득과삽입이득간의차이가모두 K-IOI-HA score와통계적으로유의한음의상관관계를보여목표이득과 REIG의차이가감소할수록 K- IOI-HA score가증가하는경향을보였고, 회귀분석에서도모두음의회귀계수가도출되었으며통계적으로유의하였다 (Table 2A). 음장청력검사에서측정한 4개의지표들에서는 Sound field PTA (db HL) 0.0 10.0 20.0 30.0 40.0 50.0 60.0 37.4±11.0 p<0.001 31.4±8.9 Sound field SDS (%) 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 78.5±16.4 91.0±8.3 94.0±6.0 p=0.001 70.0 55.0±14.9 20.0 10.0 A 80.0 Unaided Aided 2nd fitting Aided 3rd fitting B 0.0 Unaided Aided 2nd fitting Aided 3rd fitting Fig. 4. Sound field PTA calculated using six-frequency average: unaided PTA, aided PTA at 2nd fitting and aided PTA at 3rd fitting (A). Sound field SDS: unaided SDS, aided SDS at 2nd fitting and aided SDS at 3rd fitting (B). PTA: pure tone average, SDS: speech discrimination score. Table 1. The gap between target gain and REIG in speech mapping at 2nd and 3rd fitting Target gain-reig (2nd fitting) Target gain-reig (3rd fitting) p-value Soft speech level (55 db HL) 20.0±12.9 16.8±11.4 0.085 Comfortable speech level (65 db HL) 18.0±13.1 12.5±9.9 0.014* Loud speech level (75 db HL) 15.0±14.3 11.2±10.8 0.074 Roughly, the more repeated hearing aid verification, the smaller gap between target gain and REIG. But this tendency has a statistical significance only in comfortable speech level (65 db HL). *p<0.05. REIG: real ear insertion gain www.kjorl.org 291

Korean J Otorhinolaryngol-Head Neck Surg 2018;61(6):287-94 Table 2. The analysis of correlation between K-IOI-HA score and variable parameter on sound field audiometry and speech mapping in 2nd fitting Target gain-reig Pearson s coefficient Linear regression Correlation coefficient p-value Regression coefficient (95% CI) p-value R 2 A Soft speech level (55 db HL) -0.709 <0.001* -0.736 (-1.077 to -0.395) <0.001* 0.503 Comfortable speech level (65 db HL) -0.679 0.001* -0.696 (-1.047 to -0.345) 0.001* 0.461 Loud speech level (75 db HL) -0.609 0.003* -0.570 (-0.916 to -0.224) 0.003* 0.371 B Aided PTA -0.225 0.313-0.055 (-0.166 to 0.056) 0.313 0.051 Functional gain 0.139 0.536 0.028 (-0.065 to 0.122) 0.536 0.019 Aided SDS 0.080 0.725 0.026 (-0.125 to 0.176) 0.725 0.006 Gain of SDS 0.085 0.706 0.013 (-0.059 to 0.086) 0.706 0.007 Correlation between K-IOI-HA score and target gain-reig (db) in speech mapping (A), aided hearing threshold, functional gain, aided SDS and gain of SDS in sound field by Pearson s correlation analysis and linear regression analysis (B). *p<0.05. K-IOI-HA: Korean Adaptation of the International Outcome Inventory for Hearing Aids, REIG: real ear insertion gain, SDS: speech discrimination score, PTA: pure tone average, CI: confidence interval Table 3. The analysis of correlation between K-IOI-HA score and variable parameter on sound field audiometry and speech mapping in 3rd fitting Target gain-reig Pearson s correlation Linear regression Correlation coefficient p-value Regression coefficients (95% CI) p-value R 2 A Soft speech level (55 db HL) -0.705 <0.001* -1.548 (-2.274 to -0.821) <0.001* 0.497 Comfortable speech level (65 db HL) -0.684 <0.001* -1.736(-2.601 to -0.871) <0.001* 0.467 Loud speech level (75 db HL) -0.662 0.001* -1.534(-2.345 to -0.724) 0.001* 0.438 B Aided PTA -0.463 0.030* -0.260 (-0.491 to -0.028) 0.030* 0.215 Functional gain 0.077 0.734 0.147 (-0.143 to 0.436) 0.303 0.006 Aided SDS 0.155 0.491 0.029 (-0.148 to 0.207) 0.734 0.024 Gain of SDS -0.053 0.813-0.016 (-0.156 to 0.124) 0.813 0.003 Correlation between K-IOI-HA score and target gain-reig (db) in speech mapping (A), aided hearing threshold, functional gain, aided SDS and gain of SDS in sound field by Pearson s correlation analysis and linear regression analysis (B). *p<0.05. K-IOI-HA: Korean Adaptation of the International Outcome Inventory for Hearing Aids, REIG: real ear insertion gain, SDS: speech discrimination score, PTA: pure tone average, CI: confidence interval K-IOI-HA score와통계적으로유의한상관관계가나타내지않았다 (Table 2B). 3차적합에서는 speech mapping의작은소리단계, 중간소리단계, 큰소리단계에서의목표이득과삽입이득간의차이가모두 K-IOI-HA score와통계적으로유의한음의상관관계를보였고, 회귀분석에서도모두음의회귀계수가도출되었으며통계적으로유의하여 2차적합때와유사한경향을보였다 (Table 3A). 그러나음장청력검사에서측정한 4개의지표중보청기착용시순음청력역치 (aided PTA) 에서만 K-IOI-HA score와통계적으로유의한음의상관관계를확인할수있었다 (Table 3B). 고찰 보청기의조절은우선환자의청력상태를측정하여처방 공식 (prescription formula) 을통해보청기의증폭목표치를산출하게된다. 이를토대로적합하게조절된보청기는목표이득에얼마나가깝게소리를증폭시켜주고있는지객관적으로측정되어야하며, 일상생활에서느끼는주관적인착용효과를알아보기위하여보청기착용전후의수행능력이나만족도에대한평가도병행되어야한다. 5) 보청기의기계적검증방법중음장측정은변조순음 (warble tone) 이나협대역의신호 (narrow band signal) 를사용하여보청기착용시각주파수에서역치가얼마나낮아졌는지기능적이득을확인할수있다. 6) 검사방법이일반순음청력검사와유사하여비교적간단하게측정을할수있어보청기적합및기계적검증시고전적으로가장흔히시행되는검사중하나이다. 그러나일종의주관적인검사방법이므로청력역치에대한근본적인신뢰에한계가있으며, 검사시간이비교적오래걸리고어린유소아에서시행이어렵고반대측귀를 292

Speech Mapping Kim SY, et al. 차폐하고시행해야하는제한점등이있다. 7) 또한검사재현성의 95% 신뢰구간이, 실이측정검사가 3 db인데비해 8,9) 음장이득측정은약 15 db인점을고려할때 10) 재현성이낮아실이측정검사가더신뢰할수있는검사라고할수있다. 11) 실이측정은외이도에서보청기의증폭특성을측정하는것으로보청기착용전후의음압차이를비교하여보청기의이득을알아보는데사용한다. 12) 같은크기의소리자극이라도각대상의외이도내에서형성되는음압의크기가외이도공명상태에따라달라지므로소리압력이실제고막바로앞에서다른값으로바뀌게된다. 성인에서는대개 2700 Hz와 4000~5000 Hz에서두차례실이공명현상이일어난다. 13) 그로인해가령폐쇄형보청기를착용하게되면외이도에새로형성되는작은용적으로인해더큰소리압력이발생될수있다. 외이도의용적, 모양, 부피, 길이와주위조직의물리학적인요소들이관여하는외이도공명상태에의해주파수별음압이개인마다달라지게되므로실제귀에서보청기의이득이어떻게나타나는지알아보는실이측정의중요성이강조되어왔다. 14) 실이측정방법으로우선보청기를착용하지않은상태에서실이공명반응 (REUR) 을측정한후, 같은상태에서보청기를착용하고실이증폭반응 (real ear aided response) 을측정한다. 실이증폭반응과실이공명반응과의차이를전주파수범위에서연속적으로기록한곡선을실이삽입반응 (real ear insertion response) 이라고하며각주파수별로실이증폭반응과실이공명반응과의차이를실이삽입이득 (REIG) 이라고정의한다. 2) 실이삽입이득 (REIG) 의값이보청기의처방공식에서예측한목표이득및음장에서측정한기능적이득과일치하는가를확인하며적합시이득을조절해주게된다. 2) 실이측정은보청기조절과정중환자에게객관적인자료를보여줄수가있고함께참여를유도하므로보청기및조절에대한신뢰감을가지게된다는장점이있다. 15) 그러나기존의실이측정은몇가지한계점을가지고있다. 우선검사시사용되는 tone이나 noise을통해측정한이득은실생활에서의말소리나음악과같은복합음에대한이득과상당한차이를보인다. 이러한차이는보청기채널의수, 압축의속도, 압축의역치때문으로알려져있다. 11) 또한피드백제어기능이장착된고성능의디지털보청기에서는순음으로주어지는검사신호가보청기에서피드백으로인식될수있고, 잡음억제기능이보청기에장착되어있다면측정시제시되는신호가잡음으로간주되어주파수별이득을낮게책정할우려가있다. 11) 최근에는 tone이나 noise를이용한기존실이측정에서나아가실제말소리를신호음으로제시하여보청기이득을측정하는 speech mapping이각광받고있다. Speech map 은 1992년 Audioscan 사에서처음으로도입하여등록한보청기매핑환경시스템이다. 16) 말소리가실시간으로보정및조정되어제시되며개개인에맞는말소리가청영역 (speech banana) 이설정된다. 15) 외이도실이측정장치를삽입하고, 보정 (calibration) 된말소리를들려주면서증폭된소리의장기평균어음스펙트럼 (long-term average speech spectrum) 이환자의청력에따른목표이득또는말소리가청영역 (speech banana) 범위에일치하는지를확인하여보청기의이득이나다른기능을조절할수있다. 17) 또한이검사는실제말소리를작은소리 (soft speech level, 50~55 db HL), 중간소리 (comfortable speech level, 65~70 db HL), 큰소리 (loud speech level, 90 db HL) 단계로구분하여제시하므로다양한강도의실제말소리가편안한수준에서청취되도록조절할수있어기존기기에비해정교하고효율적이다. 이러한측정과정이화면에표시되므로환자가시각적으로가청영역을확인하고보청기조절과정에직접참여할수있다. 18) 본연구에서는보청기의기계적검증을위한검사로써 speech mapping을시행하고보청기적합이이루어졌을때환자의착용만족도가기능적이득을구하는음장측정결과와비교하였을때어떠한차이가있는지밝히고자하였다. 적합을거듭할수록음장청력검사에서는보청기착용시청력역치 (aided PTA) 와어음명료도가점차호전되는양상을보이며모두통계적으로유의한차이를보였다. 또한 speech mapping에서는 2차적합시에비하여 3차적합시에목표이득과 REIG의차이가감소하는경향을보여 speech mapping 을바탕으로한적합을반복할수록목표에근접한이득을줄수있음을시사하였다. 환자의주관적만족도와의상관관계분석에서 2차적합과 3차적합시의 speech mapping에서는작은소리 (55 db HL), 중간소리 (65 db HL), 큰소리 (75 db HL) 단계에서의목표이득과삽입이득간의차이가모두 K-IOI-HA score와통계적으로유의한음의상관관계를보여목표이득과 REIG 의차이가감소할수록 K-IOI-HA score가증가하는경향을보였다. 반면음장청력검사에서측정한 4개의지표중에서는 3차적합시보청기착용시순음청력역치 (aided PTA) 에서만 K-IOI-HA score와통계적으로유의한음의상관관계를확인할수있었으며, 이에대한상관계수는 0.463으로유의한상관관계를갖는다른변수들에비해상관관계가다소작음을알수있었다. 따라서 speech mapping에서측정한보청기의음향학적이득과주관적인보청기만족도와의상관관계가음장측정결과와주관적인보청기만족도와의상관관계와비교하였을때상회하는유의성을보였다. www.kjorl.org 293

Korean J Otorhinolaryngol-Head Neck Surg 2018;61(6):287-94 본연구의한계점중하나는본연구에참여한피험자가 22 명으로표본의크기가비교적작고, 양측의대칭적중등고도 감각신경성난청환자들만을대상으로하여, speech mapping 의임상적유용성정도를일반화하여적용하기는어려 울수있다. 또한보청기착용을통한주관적만족감에는보청기의음 향학적이득뿐만아니라환자개개인마다다른생활패턴, 난 청으로인해느끼는활동제약의정도에도영향을미치게되 는데본연구에서는그러한피험자의특성에대한고려가배 제되어있다. 동일한난청정도를가진환자들이동일한이 득을주는보청기를착용하여도소음이심한장소에서많은 시간을보내는사람은만족감이높지않을것이고조용한곳 에서많은시간을보내는사람은비교적높은만족감을보이 게될것이다. 따라서주관적인보청기의기능적확인을정량 화한설문지평가와보청기의음향학적이득을통한객관적 인보청기의기계적검증간의경향성을확인함에있어한계 가있다. 따라서 speech mapping 의임상적유용성을입증하 기위해서는추후피험자수를늘리고통계학적으로표본의 층화분석 (stratification) 을포함한추가연구가필요할것으 로생각된다. REFERENCES 1) Kodera K, Hosoi H, Okamoto M, Manabe T, Kanda Y, Shiraishi K, et al. Guidelines for the evaluation of hearing aid fitting (2010). Auris Nasus Larynx 2016;43(3):217-28. 2) Yoon TH. Hearing aid fitting and verification. Korean J Audiol 1998; 2(1):17-22. 3) Swan IR, Gatehouse S. The value of routine in-the-ear measurement of hearing aid gain. Br J Audiol 1995;29(5):271-7. 4) Chu HS, Cho YS, Park SN, Byun JY, Shin JE, Han GC, et al. Standardization for a Korean adaptationof the international outcome inventoryfor hearing aids: study of validity and reliability. Korean J Otorhinolaryngol-Head Neck Surg 2012;55(1):20-5. 5) Oh SH. Current opinion on hearing aids. 2nd ed. Seoul: Sejong academy;2017. p.447. 6) Cho YS. Clinical Settings for Hearing Aids. Audiol Speech Res 2016; 12 suppl 1:527-32. 7) Tecca JE. Use of real-ear measurements to verify hearing aid fittings. In: Valente M, editors. Strategies for selecting and verifying hearing aid fittings. 2nd ed, New York: Thieme Publishing;1994. p.88-107. 8) Valente M, Valente M, Goebel J. Reliability and intersubject variability of the real ear unaided response. Ear Hear 1991;12(3):216-20. 9) Valente M, Meister M, Smith P, Goebel J. Intratester test-retest reliability of insertion gain measures. Ear Hear 1990;11(3):181-4. 10) Hawkins DB, Montgomery AA, Prosek RA, Walden BE. Examination of two issues concerning functional gain measurements. J Speech Hear Disord 1987;52(1):56-63. 11) Cho YS. Management of Hearing Aids Clinic. Korean J Otorhinolaryngol-Head Neck Surg 2010;53(6):333-9. 12) Chung JH. Rehabilitation of sensorineural hearing loss: hearing aid. Hanyang Med Rev 2015;35(2):97-102. 13) Hong SH, Woo HC, Cho YS, Koh SJ, Shin MH. REUR (real ear unaided response) Performed before hearing aid fitting. Korean J Audiol 1997;1(1):64-9. 14) Noh H, Heo MG, Park SN, Park KH, Yeo SW. Feasibility of Real Ear Measurement for Hearing Aid Fitting in Preschoolers. Korean J Audiol 2010;14(3):181-6. 15) Moore BCJ. Speech mapping is a valuable tool for fitting and counseling patients. Hearing Journal 2006;59(8):26-31. 16) Cole WA, Sinclair ST. The audioscan RM500 speechmap/dsl fitting system. Trends Amplif 1998;3(4):125-39. 17) Cunningham DR, Lao-Davila RG, Eisenmenger BA, Lazich RW. Study finds use of Live Speech Mapping reduces follow-up visits and saves money. Hearing Journal 2002;55(2):43-9. 18) Ross T, Smith KE. How to use live speech mapping as part of a hearing instrument fitting and verification protocol. Hearing Review 2005; 12(6):40-9. 294