Speech Perception and Information-Carrying Capacity for Hearing Aid Users of Different Ages

Transcription

1 Audiology Neurotology Proceedings Published online: November 3, 16 Speech Perception nd Informtion-Crrying Cpcity for Hering Aid Users of Different Ages Ulrich Hoppe Thoms Hocke b Alexnder Müller c Anne Hst Deprtment of Audiology, ENT Clinic, University of Erlngen-Nürnberg, Erlngen, b Cochler Deutschlnd GmbH & Co., Hnnover, c Vivntes Hering Center, ORL Deprtment Friedrichshin Clinic, Berlin, Germny Key Words Aging Speech perception Hering id use Monosyllbic score Abstrct Hering impirment in the elderly is usully treted with conventionl hering ids; however, lrge number of older people do not chieve sufficient speech recognition with hering ids. The im of the study ws to describe speech perception with hering ids in comprison to pure-tone hering loss nd mximum speech recognition scores for phonemiclly blnced words. Dt from 392 hering id users with different degrees of hering loss were evluted retrospectively. In prticulr, pure-tone thresholds, the mximum monosyllbic word score, nd the monosyllbic word score in quiet t converstionl level with hering id were nlysed. The results showed tht speech perception scores decline with incresing ge. Even when corrected for puretone hering loss, significnt decline in speech recognition scores fter the ge of 8 yers ws observed. Regrding the mximum monosyllbic word score, the effect is smller but still observble; thus, speech recognition with hering ids is significntly lower for older subjects. This cn be ttributed prtilly to the reduction of the informtion-crrying cpcity in this group. 16 The Author(s) Published by S. Krger AG, Bsel Introduction Deteriortion in hering bility tht occurs with ging is complex process tht cn vry in severity from minor to substntil. According to vn Rooij et l. [199], the proportion of elderly persons with problems in perceiving speech doubles per decde of life from 16% t the ge of 6 to 32% t the ge of 7 nd to 64% t the ge of 8. According to the ISO report for thresholds of hering loss versus ge, every second person bove 65 yers of ge needs hering id (HA) mplifiction. Left untreted, presbycusis of moderte or greter degree ffects communiction nd reduces qulity of life substntilly. Where HAs no longer provide benefit, cochler implnttion is the tretment of choice with excellent results even in elderly subjects [Hst et l., 15]. Most severely hering-impired dults hve history of some HA use where they hve experienced stedily diminishing speech perception bility. As the min gol of cochler implnttion is the improvement of speech understnding, beyond wht is fesible by conventionl mplifiction, thorough HA evlution is dvisble prior to cochler implnt (CI) surgery. One importnt outcome mesure in HA evlutions is the perception of monosyllbic words t converstionl level. An individul s speech recognition score with HAs t converstionl level [SRS 65 (HA)] vries drmticlly with pure-tone hering E-Mil krger@krger.com 16 The Author(s) Published by S. Krger AG, Bsel 14 33/16/217 16$39.5/ This rticle is licensed under the Cretive Commons Attribution- NonCommercil-NoDerivtives 4. Interntionl License (CC BY- NC-ND) ( Usge nd distribution for commercil purposes s well s ny distribution of modified mteril requires written permission. Prof. Dr. Dr. Ulrich Hoppe Deprtment of Audiology ENT Clinic, University of Erlngen-Nürnberg Wldstrsse 1, DE 9154 Erlngen (Germny) E-Mil uk-erlngen.de

2 Freiburg monosyllbic score (%) A: PB mx B: SRS 65(HA) PBmx SRS65(HA) (% ptients) 3 1 A B b Fig. 1. Speech recognition score for Freiburg monosyllbic words s function of pure-tone loss mesured s pure-tone verge for thresholds t.5, 1, 2, nd 4 khz (4FPTA). The solid line represents PB mx, nd the dotted line represents scores t 65 db with HAs [SRS 65 (HA)]. b Difference of the functions shown bove [PB mx SRS 65 (HA)]. loss. However, the verge dependency between the two vribles cn be chrcterized by logistic function [Hoppe et l., 14, 15] with n nticipted 1% t mild hering losses nd nerly zero for profound hering loss. This function is shown in figure 1. In prior study [Hoppe et l., 14], similr function ws found for the mximum phonemiclly blnced word score (PB mx ) mesured under hedphones ( fig. 1, dotted line). The PBmx defines the mximum monosyllbic word recognition score for phonemiclly blnced words [Gelfnd, 1997]. According to Hlpin nd Ruch [8], the PB mx cn be used s n estimtor for the informtioncrrying cpcity (ICC) of the uditory system. Within the process of HA evlution, the PB mx chrcterizes the potentil for the best possible speech recognition with HAs t converstionl level of 65 db sound pressure level (SPL). As shown in figure 1, not ll HA users cn trnsfer their full ICC into speech recognition scores using conventionl mplifiction, nd gp of up to 3% remins. Figure 1 b shows tht this gp depends on the mount of pure-tone hering loss with mximum reched for severe hering loss levels. For severe hering losses, the potentil HA performnce is limited by n insufficient residul dynmic rnge [Zwrtenkot et l., 14] nd the versiveness to the high levels of coustic mplifiction [Hoppe et l., 14]. Additionlly, the effect of ging on cognitive processes is mjor contributing fctor ffecting HA performnce [Wlden nd Wlden, 4; Müller et l., 16]. The im of our retrospective nlysis ws detiled investigtion of the ge dependency of the ICC. Another question ws whether the perceptul gp between PB mx nd SRS 65 (HA) depends on the subject s ge. Methods In totl, HA evlutions of 392 subjects with bilterl sensorineurl hering loss performed in the Audiologicl Centres of Erlngen (n = 156) nd Berlin (n = 236) were nlysed retrospectively. The dt from 784 ers were nlysed seprtely. The men ge of the subjects ws 65 ± 16 yers nd rnged from 18 to 96 yers. The dt were collected s prt of clinicl routine for HA performnce ssessment. All subjects hd been supplied with HAs nd hd t lest 3 months of experience using them. Approximtely 5% of the subjects were first-time users. All hd completed the HA selection nd fitting process t lest 3 months before the visit. Prior to ided hering ssessment, the HAs were techniclly checked. All ptients ttended follow-up visit with their HA professionl before the evlution visit. Only ntive Germn-speking subjects with no known mentl disbilities influencing udiometric test results were included in the nlyses. Subjects with ir-bone gps of more thn 5 db were excluded from the nlyses. Ech er ws tested seprtely. The pure-tone verge threshold for the frequencies.5, 1, 2 nd 4 khz ws clculted for ech er. Speech udiometry using Freiburg monosyllbic words ws mesured vi hedphones in the unided condition for ech er. The speech stimuli were presented t 65 db SPL initilly, nd the corresponding speech recognition score, i.e. correct word score in percent, ws recorded. The presenttion level ws incresed stepwise by 1 15 db until mximum score of 1% ws chieved or Speech Perception in Elderly Hering Aid Users 17

3 1 8 PBmx (%) 6 4 Fig. 2. Sctter representtion of the mximum monosyllbic score (PB mx ) s function of 4-frequency verge t.5, 1, 2, nd 4 khz (4FPTA). Ech dot represents the result from one er the mximum score chievble (PB mx ) tht ws below the ptient s uncomfortble loudness level. For ll clcultions, the MthWorks TM Mtlb softwre ws used. Results Figure 2 shows sctter plot of the PB mx scores for ll 784 ers s function of the verge pure-tone loss. While there is strong tendency for lower PB mx with incresing 4-frequency pure-tone verge, there is lrge vribility in the dt. For severe hering loss between 7 nd 8 db, for exmple, PB mx vries between nd 1% but the dt lso revel tht subjects with PB mx of 4% my hve hering loss rnging from 5 to 118 db HL. The difference vlue between the verge PB mx performnce function nd ech individul PB mx ws clculted (i.e. curve A in fig. 1 ). This djustment llows for n investigtion of hering loss independently of other influencing fctors. Figure 3 shows the results of the djusted PB mx versus the subjects ge. For trnsprency, dt were summrized in groups of one decde nd shown s box plots to illustrte the dt distribution. Medin vlues re shown s horizontl line within ech box, limited by the upper nd lower qurtile. Lower nd upper whisker plots represent 5 nd 95% percentiles, respectively. The dshed line denotes the zero line indicting verge performnce. With incresing ge for ech subgroup, tendency for lrger discrepncies from the verge performnce is observed. For those below 7 yers of ge, no systemtic devition from the verge performnce line cn be found. Above 7 yers of ge, cler trend for decresing performnce is present. Discrepncies to the verge performnce increse from 3% (7 8 yers) to 7% (8 9 yers) nd 18% (>9 yers). Additionlly, the vribility within ech ge group increses with incresing ge: interqurtile rnges vry from 15 17% for younger groups to 26% for the group ged 8 9 yers. Discussion Successful decoding of speech signls requires functionl integrity t ll stges long the uditory pthwy including the inner er, cochler nerve, brinstem, nd ultimtely the uditory cortex. From the functionl point of view, not only is sensitivity importnt, but lso sufficient temporl nd spectrl resolutions re required for speech recognition nd comprehension. This study investigted the deteriortion of speech recognition in the elderly. While there is gret del of knowledge bout the loss of threshold sensitivity for pure tones with incresing ge, little is known bout the progressive decline of speech recognition in the elderly. The study shows tht speech recognition is ffected to gret- 18 Hoppe/Hocke/Müller/Hst

4 4 PBmx A (% ptients) Fig. 3. Difference between individul PB mx scores nd verge performnce (A) s function of ge. Box plots summrize dt of one decde from 4 to 9 yers. Figures within the box plots represent the number of ers within the rnge. < >9 Age (yers) er extent thn would be predicted from the pure-tone thresholds, lone, for the older elderly group of >8 yers of ge. In prticulr, the PB mx, mesure of the ICC, is significntly reduced in this group compred to the younger elderly group. Recent reports hve demonstrted tht ided speech perception for older HA users is significntly lower thn for younger dults [Hoppe et l., 14; Müller et l., 16]. Though HA fittings were techniclly verified, older HA listeners 7 yers chieved speech recognition scores tht were 1 % lower thn for younger HA listeners. The primry hypothesis ws tht the HA users in the more senior groups do not receive the pproprite mplifiction nd sound qulity from their HAs. Our study, however, shows tht even when presenting mplified speech stimuli vi hedphones, the speech recognition score is significntly reduced in the older elderly group compred to the younger elderly groups. This reduced ICC for older listeners is supported by models of degenertion of the centrl uditory pthwy tht indicte tht feture extrction nd pttern recognition for uditory ptterns such s speech re reduced in the elderly [Humes, 1996]. Currently, the question remins open whether the reduced speech recognition depends on cognitive fctors locted in the cortex or on uditory signl processing dysfunction tking plce t cochler or brinstem levels. On the other hnd, number of studies indicte tht older subjects who re provided with CI cn chieve speech perception scores tht re identicl or very similr to younger CI users [Nkjim et l., ; Orbi et l., 6; Clrk et l., 12; Hst et l., 15]. Further, elderly CI listeners lso demonstrte benefit from individully tilored uditory trining therpy tht cn result in uditory outcomes mrginlly below those observed for younger CI users [Schumnn et l., 14]. The use of the PB mx s n estimtor of the ICC ws first proposed by Hlpin nd Ruch [8]. They demonstrted tht the PB mx is more vlid mesure for n estimte of everydy speech recognition thn the pure-tone threshold levels in subjects with sensorineurl hering loss. As shown in figure 2, identicl verged pure-tone hering losses result in very different ICC. Obviously, the 4-frequency pure-tone verge is rough mesure only for overll hering bility nd considers neither influencing temporl spects nor the frequency chrcteristics of hering loss; therefore, the PB mx provides importnt dditionl informtion. However, when estimting speech perception in everydy life one hs to consider tht the PB mx is not chieved in mny cses. As shown in figure 1, differences between PB mx nd speech recognition scores with HA t 65 db SPL cn be s lrge s 3%. Considering the simple mesurement of the PB mx, it provides n excellent tool when screening for CI cndidcy Speech Perception in Elderly Hering Aid Users 19

5 [Hoppe et l., 15]. As n exmple, when subject s PB mx is below 6% for mplified speech under hedphones for monosyllbic words, it is fesible tht their corresponding monosyllbic word score t converstionl level vi n HA will be 3% or lower. Such poor performnce with conventionl mplifiction would clerly mke this individul cndidte for CI ccording to the commonly pplied udiologicl criterion cross CI clinics. Cliniclly, evlution of the PB mx requires mesurements by the stndrd udiometer nd hedphones only nd is independent of the ctul HA settings. As such the PB mx provides simple nd redily vilble method to ll udiology centres for the identifiction of potentil CI cndidtes mongst the hering-impired elderly popultion for further referrl to nd evlution by specilist implnt tems. Conclusion The PBmx provides vlid estimtor for the ICC nd hence lso the mximum bility for speech recognition nd understnding in everydy life. In contrst to puretone thresholds, it considers both temporl spects nd suprthreshold uditory processing involved in speech perception. Therefore, estimtion of the ICC vi mesurement of the PB mx should be used routinely during the evlution for CI cndidcy for ptients of ny ge. Disclosure Sttement T. Hocke is n employee of Cochler Deutschlnd GmbH & Co. KG. The other uthors (U.H., A.M., A.H.) stte tht there is no conflict of interest to be disclosed. References Clrk JH, Yegle J, Arbje AI, et l: Cochler implnt rehbilittion in older dults: Literture review nd proposl of conceptul frmework. J Am Geritr Soc 12; 6: Gelfnd SA: Essentil of Audiology. New York, Thieme, Hlpin C, Ruch SD: Clinicl implictions of dmged cochle: pure tone thresholds vs informtion crrying cpcity. Otolryngol Hed Neck Surg 8; 14: Hst A, Schlücker L, Digeser F, Liebscher T, Hoppe U: Speech perception of elderly cochler implnt users under different noise conditions. Otol Neurotol 15; 36: Hoppe U, Hst A, Hocke T: Speech perception with hering ids in comprison to pure-tone hering loss. HNO 14; 62: Hoppe U, Hst A, Hocke T: Audiometry-bsed screening procedure for cochler implnt cndidcy. Otol Neurotol 15; 36: Humes L: Speech understnding in the elderly. J Am Acd Audiol 1996; 7: Müller A, Hocke T, Hoppe U, Mir-Slim P: The ge effect in evlution of hering id benefits by speech udiometry. HNO 16; 64: Nkjim S, Iwki S, Fujisw N, Ymguchi S, Kwno M, Fujiki N, Nito Y, Honjo I: Speech discrimintion in elderly cochler implnt users. Adv Otorhinolryngol ; 57: Orbi AA, Mwmn D, Al-Zoubi F, Seed SR, Rmsden RT: Cochler implnt outcomes nd qulity of life in the elderly: Mnchester experience over 13 yers. Clin Otolryngol 6; 31: Schumnn A, Hst A, Hoppe U: Speech performnce nd trining effects in the cochler implnt elderly. Audiol Neurotol 14; 19: Vn Rooij J, Plomp R, Orlebeke J: Auditive nd cognitive fctors in speech perception by elderly listeners. II. Multivrite nlysis. J Acoust Soc Am 199; 88: Wlden TC, Wlden BE: Predicting success with hering ids in everydy living. J Am Acd Audiol 4; 15: Zwrtenkot JW, Snik AF, Mylnus EA, Mulder JJ: Amplifiction options for ptients with mixed hering loss. Otol Neurotol 14; 35: Hoppe/Hocke/Müller/Hst