听神经病患者普通话单音节识别错误模式分析

目的 分析听神经病(auditory neuropathy,AN)患者单音节识别测试的错误模式,总结AN患者在言语识别障碍方面的特点,探讨单音节言语识别测试对于AN诊断的作用.方法 AN患者16例,共32耳;根据听力图曲线分为两个亚组:上升型听力组(15耳)和非上升型听力组(17耳).感音神经性聋患者22例(共32耳)作为对照组.使用自行编制的言语测试材料在较高的测试强度下进行单侧单音节识别测试,记录每个测试耳的单音节识别得分和错误模式.错误模式分为8种:仅声母错、仅韵母错、仅声调错、声母错+韵母错、声母错+声调错、韵母错+声调错、声韵调全错、无反应.结果 AN患者单音节总体识别得分低于感音神经性聋患者(P<0.001).上升型听力的AN患者其单音节识别率、声母、韵母、声调识别率与对照组感音神经性聋患者差异无统计学意义;非上升型听力的AN患者单音节识别率、声母、韵母、声调识别率均低于感音神经性聋患者(P值均<0.001).AN患者与感音神经性聋患者的单音节识别错误模式构成比差异具有统计学意义(P<0.001),前者涉及声调识别的错误所占比例较大.上升型听力AN患者单音节识别率和声母、韵母、声调识别率均高于非上升型听力AN患者(P值均<0.001).上升型听力AN患者与非上升型听力AN患者的单音节识别错误模式构成比差异具有统计学意义(P<0.001),前者涉及声调和韵母的识别错误所占比例较大.结论 普通话四声识别能力差是AN患者区别于感音神经性聋患者的一个重要特征.上升型听力AN患者与非上升型听力AN患者在单音节识别率、韵母和声调错误所占比例等方面存在特征性差异.心理物理测试对AN的诊断具有潜在的重要作用.     

耳蜗死区对感音神经性听力损失患者言语识别能力的影响

目的 探究耳蜗死区在感音神经性听力损失(sensorineural hearing loss,SNHL)患者中的存在情况及其对言语识别能力的影响.方法 采用纯音听阈测试筛选出41例(81耳)感音神经性听力损失患者,经均衡噪声阈值测试将患者分为有耳蜗死区组(35耳)和无耳蜗死区组(46耳),分别进行言语识别阈(SRT)和言语识别率(SDS)测试,分析81耳耳蜗死区的分布及其对言语识别能力的影响.结果 41例(81耳)感音神经性听力损失患耳中有35耳(43.21％,35/81)存在耳蜗死区,其中轻度SNHL患耳耳蜗死区检出率为0(0/11),中度SNHL患耳耳蜗死区检出率为24.1％(7/29),重度SNHL患耳耳蜗死区检出率为66.7％(24/36),极重度SNHL患耳耳蜗死区检出率为80.0％(4/5),不同听力损失程度耳耳蜗死区检出率差异有统计学意义(P＜0.05);高频耳蜗死区(16耳)明显多于低频耳蜗死区(8耳),但两者的言语识别能力差异无统计学意义(P＞0.05);有耳蜗死区患者的言语识别阈及言语识别率分别为61.63±16.76 dB HL,86.35％±12.03％,无耳蜗死区的患者分别为75.54±9.56 dBHL,64.97％±20.84％,二者间差异有统计学意义(P＜0.05).结论 听力损失越重,耳蜗死区检出率越高;高频耳蜗死区较低频常见,且存在耳蜗死区的感音神经性听力损失患者言语识别能力明显低于无耳蜗死区的患者.     

频域信息在感音神经性听力损失患者普通话声调感知中的作用

目的 探讨言语频域包络信息和精细结构信息对听力正常和感音神经性听力损失人群汉语普通话声调识别的作用.方法 采用线性预测编码技术对具有相同音节但不同声调的单音节字进行频域包络与精细结构的分离,将具有相同音节不同声调的单音节字的频域包络信息进行互换,合成128个新的具有来自于不同声调的频域包络和精细结构信息的“单音节字”.利用这些“单音节字”测试20名听力正常人与48例感音神经性听力损失患者(20例中度、20例中重度及8例重度)的声调感知能力.利用SPSS 15.0软件进行统计分析.结果 听力正常受试者99.7％的声调识别基于频域精细结构信息,中度至重度听力损失患者基于频域精细结构感知声调的识别率分别为97.7％,96.3％和83.0％.各组受试者均未依靠频域包络信息识别声调.三组听力损失患者依靠频域精细结构识别声调的能力均与听力正常受试者存在差异(x2=59.2,P＜0.001).感音神经性听力损失患者利用频域精细结构信息识别声调的能力与其听力损失程度呈负相关关系(r=-0.643,P＜0.001).结论 频域精细结构信息在普通话声调识别中起主要作用,精细结构存在时,频域包络信息对声调识别不起作用.感音神经性听力损失患者利用频域信息感知声调的模式与听力正常人群相似,伴随听力损失程度加重,其利用频域精细结构信息感知声调的能力缓慢降低.     

听神经病谱系障碍患者噪声下言语识别能力研究

目的分析听神经病谱系障碍(Auditory neuropathy spectrum disorder,ANSD)患者噪声下言语识别能力。方法利用普通话版噪声下听力测试(Mandarin Hearing In Noise Test,MHINT),分别测试30例ANSD患者,16例感音神经性听力损失(sensorineural hearing loss,SNHL)患者和12例听力正常者在安静情况下和信噪比分别为15,10,5,0 d B的噪声条件下的言语识别能力。结果 ANSD组在噪声条件下的言语识别率显著低于SNHL组和听力正常组(P<0.05);ANSD组在安静条件下与信噪比为15 d B条件下的言语识别率差异无统计学意义(P>0.05),然而与信噪比为10、5和0d B条件下言语识别率差异均具有统计学意义(P<0.05)。安静情况下及噪声条件下,SNHL组和ANSD组言语识别能力与其听力损失程度均呈显著负相关(P<0.01)。结论 ANSD患者的言语识别能力较SNHL患者显著降低,大多数ANSD患者安静条件下言语识别尚可,但噪声情况下言语识别能力显著下降;噪声条件下言语测试对ANSD的诊断具有潜在的重要作用。     

感音神经性听力损失患者不同噪声模式下的言语识别能力研究

目的　研究不同噪声模式对听力正常者和感音神经性听力损失者言语识别能力的影响。方法　通过MATLAB软件播放儿童版汉语普通话噪声下言语测试句表,测试25名听力正常受试者和20例感音神经性聋受试者分别在安静环境、语谱噪声、双人语噪声下的言语识别能力,分析两者在安静和两种噪声模式下对语句感知能力的差异。结果　随信噪比降低,听力正常者在语谱噪声下言语识别率低于双人语噪声,但差异无统计学意义（P＞0.05）。感音神经性听力损失者在信噪比+5 dB时,双人语噪声下言语识别率低于语谱噪声,且差异有统计学意义（P＜0.05）。结论 　两种噪声模式对比,听力正常者在双人语噪声下言语识别率更高,感音神经性听力损失者在语谱噪声下言语识别率更高。     

极重度聋人模式言语助听下的汉语声调识别

汉语声调具有重要的区别字义的功能,模式言语助听装置正是为极重度聋人感知高频辅音和基频信息而设计。本文就模式言语助听下的汉语普通话声调识别进行系统测试。结果发现,听力正常者在自然语音无听力放大条件下和在模式言语助听下,其声调错误识别率无显著差异。说明模式言语提供的正弦化基频信息可为听力正常者感知成声调信息。极重度聋人在模式言语助听下声调错误识别率较在传统助听下有显著降低,说明模式言语助听能为极重度聋人提供更易分辨的声调信息,有助于提高他(她)们的看话能力,是其实现听力语言康复的有效手段之一。     

正常人单音节词及语句识别-强度函数测试

目的:对难度等价性一致的普通话言语测听材料(MSTMs)中的单音节词表和句表进行分析,以期描绘出基于此测试材料的听力正常人识别-强度函数曲线.方法:选取18～25岁具有大专以上学历、且日常生活中以普通话作为交流方式的40例听力正常人作为受试者,对其中8例受试者进行预试验,从而获得正式测试时所需的给声强度;对其余32例受试者进行正式的言语识别测试.采用MSTMs中经过等价性评估的7张(每张50词)单音节词表和15张句表(每表50个关键词)作为测试材料.使用SPSS11.0软件对数据进行分析.结果:MSTMs单音节词表的言语识别率与给声强度间的函数关系的线性部分为Y=3.194X-46.147,识别率为50%时的给声强度为30.1 dBSPL;MSTMs句表的言语识别率与给声强度间的函数关系的线性部分为Y=7.419X-121.744,识别率为50%时的给声强度为23.1 dBSPL.结论:本研究初步建立了基于具有难度等价性的7张普通话单音节测听词汇表和15张普通话语句测听词汇表的正常人识别-强度函数曲线,为临床应用提供了基于MSTMs的正常听力者的鉴别标准.     

听神经病患者噪声下言语测听临床应用与分析

目的对比听神经病患者安静与噪声下言语识别率的差异并与正常受试者、感音神经性听力损失组、听神经瘤组进行比较。方法测试在符合国家标准的隔声室内进行,纯音测试及言语测试应用校准后丹麦耳听美Conera听力计Otosuite(版本号4.82)联结计算机输出言语声,受试者佩戴头戴式耳机TDH-39、B71骨导振动器测试纯音。言语识别测试材料采用解放军总医院郗昕编制的《普通话言语测听—单音节识别测试》词表,在安静和噪声环境下,分别测试听神经病患者10例、感音神经性聋患者11例、听神经瘤患者11例和听力正常受试者10例患者在平均听阈、阈上10dB、20dB、30dB处的言语识别率以及信噪比为-0、-5、-10、-15dB的言语识别率得分。结果听神经病患者在噪声下言语识别能力明显低于听神经瘤组、感音神经性听力损失组以及正常听力组(P<0.05);具有相似听力阈值及听力曲线的AN患者,给予安静及不同噪声强度测试,可呈现较差及较好二级分化的SRS曲线;正常组在信噪比为-0、-5、-10、-15dB的环境下,信噪比为10dB时对比自身安静环境言语识别得分无显著性差异(P>0.05),而听神经病组、听神经瘤组和感音神经性听力损失组在-10 SNR处均有显著性差异(P<0.05)。听神经病患者在安静环境下随刺激声强度的升高会出现"回跌"现象。听神经病患者总体水平在安静与噪声环境下纯音听阈与言语识别得分均与无相关性(R2=0.07),其他三组呈现负的弱相关或强相关。结论安静环境下言语识别能力较好的听神经病患者在噪声环境中下降程度更为显著,相对于安静环境言语识别测试更加敏感;采用平均阈上30dB及-10dB信噪比测试,所得言语识别得分可作为临床评价言语功能的敏感指标,且对于听神经病诊断和病变定位及程度分析更具有现实意义,能够更全面评估听神经病患者的言语交流能力。     

感音神经性听力损失患者助听后言语感知能力的评价

目的本研究对感音神经性听力损失患者助听器选配后的言语识别能力进行评价,并分析听力损失程度与年龄对助听后言语康复效果的影响。方法 30名感音神经性听力损失受试者,男13名,女17名,年龄26-86岁,双侧听力损失程度对称,双耳0.5-4 k Hz频率下纯音听力阈值(PTA0.5-4 k Hz)平均值40~75 d B HL。所有受试者均选配PhonakBolero Q50系列耳背式助听器。使用汉语普通话言语测试软件(Mandarin Speech Test Materials,MSTMs)进行裸耳和助听后安静与噪声环境下言语识别能力测试。结果(1)助听后,安静环境下的双音节识别率平均提高35.1±19.5%;噪声环境下语句识别率平均提高32.8±22.8%;(2)助听后言语识别能力与听力损失程度呈显著负相关关系;(3)助听优势高于平均水平的受试者纯音听阈均大于50 d B HL,但存在个体差异大的特点。结论助听器选配可以有效帮助感音神经性听力损失患者提高言语识别能力,但听力损失程度不是唯一影响助听效果的因素,助听后言语识别能力的改善存在较大个体差异。     

汉语普通话单音节测听表的建立与评估

目的 建立一套普通话单音节测听表并验证其效度、信度和敏感度,期望成为国内标准化的言语识别率测听材料.方法 遵循简短、音位平衡、常用、覆盖等原则,生成30张音位平衡单音节表,每表对应25个常用汉字.由专业男性播音员朗读,经数字化录音及声学处理,录制成CD.研究分为三个阶段:①招募60名听力正常年轻人,采用随机区组设计:言语测听表号与测听强度均衡排布,每一受试者均变换6种强度(言语听力级-1、5、11、15、21、27 dB)以循环顺序聆听全部30张单音节表.计算每表每一声级下的言语识别率得分,以logistic曲线回归来拟合识别率-强度(P-I)函数.对30张词表的识别率进行双因素(表号、强度)方差分析和Post-Hoc两两比较,得到22张等价表.②北京22名听力正常年轻人,采用拉丁方设计,在言语听力级10 dB强度下依次测试22张等价表的识别率.间隔6～35 d,在完全相同的条件下重新进行第二轮识别率测试.两轮测试的识别率经"合理化"的反正弦变换后,逐表汇总两轮测试分差,该分差值在22名受试者中的标准差为9.3%,转化成95%置信度下的临界分差为18.3%.③采用拉丁方设计方案,对18名感音性听力损失患者在其纯音平均听阈上30 dB或最大舒适级,测试其对18张等价表的识别率.间隔1～16 d在相同条件下再次进行测试.两轮测试的识别率经"合理化"的反正弦变换后,分别为(68.0±15.9)%和(69.2±14.6)%,配对t检验,P=0.107.两轮测试分差,在18名患者中的标准差为8.3%,转化成95%置信度下的临界分差为16.3%.结果 创建了一套22张等价的标准化的言语识别率测听表.每表由音位平衡的25个单音节构成,播放时间约2 min.听力正常人的单音节识别阈为言语听力级(8.30±0.84)dB,P-I函数的斜率为(4.0±0.3)%/dB.临床评判受试者言语识别率差异时,只要分差超过临界分差--正常人(18.3%)、患者(16.3%),即可确认具有统计学意义上的显著性差异.结论 成功建立起一套普通话单音节测听表,具有较高的效度、信度和敏感度,便于临床应用.     

Sweep-frequency tympanometry: its development and diagnostic value

This reports a newly developed tympanometric system using a sweep-frequency probe tone. For a sweep-frequency tone ranging from 220 to 2 000 Hz, measurements of sound pressure (P) and phase were performed at ear canal pressures of 0 and -200 mm H2O. The results were expressed as a sound pressure curve (P0-P-200 in decibels), a phase curve (formula: see text) and a polar curve (formula: see text) against probe tone frequency. Both the frequency at which the sound pressure curve crossed the 0-dB difference line and the peak frequency of the phase curve shifted lower than normal for ossicular disruption and higher than normal for ossicular fixation. Changes in the sound pressure curve and in the phase curve were exaggerated for ossicular disruption and limited for fixation. As the result of these, the polar curve showed an expanded type for disruption and a compressed type for fixation. A review of 220-Hz tympanograms and of the polar curves for 10 patients demonstrated that the latter permitted a better discrimination among ossicular disorders.     

畸变产物耳声发射在舰艇艇员听力调查中的应用

目的了解舰艇艇员的听力状况并探讨纯音听力图与DPOAE听力图的关系。方法对100名(200耳)舰艇艇员进行纯音、声导抗、DPOAE测试,测试仪器均为GSI系列产品。根据纯音测听结果将其分成正常、低频听力下降、高频听力下降及全频听力下降四个组,并结合纯音听力图与DPOAE听力图进行比较。结果纯音听阈正常组的DPOAE检出率及DPOAE振幅明显高于低频听力下降组、高频听力下降组及全频听力下降组(P＜0.01或0.05);DPOAE听力图与纯音听力图个各在频率均有很好的对应关系。结论DPOAE作为一种评价耳蜗毛细胞功能状态,在征兵、部队听力普查中较传统的纯音听阈测试更有意义。     

听觉中枢功能状态对老年感音神经性听障患者听力语言康复的影响

目的探究听觉中枢功能状态对老年感音神经性听障患者听力语言康复的影响。方法选取我院2018年1月~2020年8月诊治的老年感音神经性听障患者109例,分别进行纯音测听、助听听阈测试、皮层听觉诱发电位测试及言语识别测试。以55 dB声压级(sound pressure level,SPL)下皮层听觉诱发电位P1是否全部引出波形分为A组(引出波形,n=47)和B组(未引出波形,n=62);比较两组患者纯音测听、助听听阈结果和言语识别率,分析助听听阈与听觉诱发电位P1波潜伏期、幅值的相关性。结果A组患者纯音听阈显著高于B组(P<0.05);A组在低频、中频、高频的助听听阈值均显著低于B组(P<0.05)。配戴助听器后两组患者的言语识别率均增加,且A组显著高于B组(P<0.05)。P1波幅值随着刺激强度增强逐渐降低,助听听阈随着引出P1的刺激强度增强逐渐提高。助听听阈与幅值呈显著负相关(P<0.05),与P1波潜伏期无相关性(P>0.05)。结论皮层听觉诱发电位与助听听阈测试结果具有相关性。     

健听人在不同本底噪声环境中的听阈值分析

目的计算健听人在不同本底噪声环境中的听阈值,通过与在标准测听环境中的结果相比较,确定非标准测听环境中听阈的修正值,探讨听力残疾抽样调查中最低环境本底噪声级的控制值。方法在不同的本底噪声环境中,采用纯音测试和声场测试的方法,对50人(100耳)分别进行测听。结果研究结果显示,在本底噪声分别为45dB(A)、50dB(A)、55dB(A)的测听环境中,健听者的纯音测试听阈值分别为15dBHL、20dBHL、25dBHL,与标准测听环境中的听阈差值分别为10dBHL、15dBHL、20dBHL;声场测试听阈值分别为25dBHL、30dBHL、35dBHL,与标准测听环境中的听阈差值分别为15dBHL、20dBHL、25dBHL;统计结果显示,不同本底噪声环境中,健听人的听阈值具有显著性差异。结论根据健听人在不同本底噪声环境中与在标准测听环境中的听阈差值,可以确定在非标准测听室及相应本底噪声环境中的听阈修正值,也可以确定听力残疾评定允许测听环境最高噪声级。     

New hearing test for functional deafness--the procedure to estimate the genuine hearing threshold]

This report describes a new procedure for examining functional deafness with binaural sound stimulation. This new hearing test can estimate the genuine pure tone hearing threshold quantitatively at every frequency by using the ordinary audiometer. In the case of the nonorganic deafness, even if the hearing disorders are bilateral or hemilateral, we believe that measuring auditory threshold separately, causes the deterioration of the threshold. Therefore, this procedure is designed so that the subject may not be aware of testing the auditory acuity of each ear, and utilizes the response of the phantom sound image in the head by simultaneous binaural presentation of sound stimulation. Our strategy is based on the following facts. If the normal subject has the same pure tone threshold level in both ears, the phantom sound image is formed in the median plane of the head by the equal suprathreshold tone level presented simultaneously in each ear. In the case of a unilateral auditory disorder, the sound image is localized to the center of the head only when sound stimulation louder than the threshold level of affected ear is given to both ears at the same time. Simultaneous binaural sound stimulation at a lower level than the threshold of the affected ear forms a lateralized sound image to the unaffected ear in the head. For patients with bilaterally similar hearing loss, the sound image is not formed if the stimulation is less than the threshold level of the pure tone. The band noise in the phase of each frequency with 50 dB HL was given binaurally to 10 normal hearing subjects, and the localization of the sound image formation was examined. This experiment confirmed that around the occipital region of the median plane in all subjects. Furthermore, comparing the formation threshold of the median plane image with the pure tone auditory threshold, proved that there was no significant difference statistically in either value. As a next step, 15 patients with unilateral sensorineural deafness were examined with this technique and we knew that the median sound images would not be formed with stimulation less than the pure tone auditory threshold of the affected ear. For clinical application, patients were classified into two groups with unilateral (6) and bilateral (2) functional deafness, and examined. Midline sound images definitely were formed with the lower magnitude of sound than the pure tone threshold by hemilateral nonorganic deafness. The difference of the forming threshold of the median sound image and the average of pure tone hearing level of the affected ear were maximum 100 dB, minimum 35 dB, and mean 69.4 dB. Furthermore, the difference of the median image forming threshold and the average hearing level of the unaffected ear were maximum 35 dB, minimum 0 dB, and mean 15.4 dB. In bilateral disorders, the midline plane sound image was formed with the corresponding level of the pure tone value in one subject, though the other one was determined by the maneuver method because it did not form a midline sound image. In conclusion, this examination can be readily used to estimate the genuine hearing threshold of the functional deafness.     

唇读信息对正常人语句识别的影响

目的通过单视觉(唇读)、单听觉、视觉与听觉结合对正常青年人言语识别率的对比测试来说明唇读对语句识别的影响。方法选择正常听力青年大学生27名,分别在只看视频(唇读)、只听声音、视频和声音结合的情况下用新编中文普通话版嘈杂语噪声下语句识别表测试其言语识别率。结果在单视觉、单听觉和视觉与听觉结合的情况下,27例受试者平均言语识别率分别为33.1%±10.1%、40.8%±10.6%、91.5%±3.9%,视觉与听觉结合情况下的平均言语识别率显著高于单视觉、单听觉,差异有统计学意义(P<0.05)。结论在噪声环境下,唇读信息可明显提高正常人对语句识别的能力。     

不同听觉干预手段对聋儿声调辨别能力的影响

目的了解聋儿对声调的识别能力,以指导聋儿的言语康复训练。方法将受试对象分为3组:人工耳蜗组、助听器组和对照组。人工耳蜗组和助听器组均为双耳重度或极重度听力损失患儿。人工耳蜗组43例,其中男20例,女23例,人工耳蜗植入年龄在2.5～7岁;助听器组41例,男22例,女19例;对照组28例为听力正常儿童,男13例,女15例,年龄3～6岁。测试3组儿童对单音节词声调、扬扬格词声调的识别能力。结果人工耳蜗组对单音节词、扬扬格词声调的识别能力显著优于助听器组(P<0.01),但弱于正常对照组(P<0.01)。结论不同的听觉干预手段对聋儿声调识别能力有影响,人工耳蜗对重度或极重度听力损失的儿童较助听器有更好的声调识别能力。     

人工耳蜗植入儿童听觉康复效果观察

目的观察语前聋患儿在人工耳蜗开机后一年内听觉能力的发展状况,为康复教学工作提供参考。方法对52例在南京大学医学院附属鼓楼医院进行人工耳蜗植入手术并开机和定期调机的患儿,于开机后半年和一年时分别进行声场评估,得到每位患儿的术后平均听闽,同时由康复教师对患儿进行韵母、声母、声调、单音节词、双音节词、三音节词、短句和选择性听取等8项评估。使用SPSS10．0统计学软件对半年和一年时各项评估结果进行组内纵向统计学比较,并分别就两次言语识别能力评估中音节要素、词语方面各自所含测试项进行组间横向统计学比较。结果开机后半年与一年患几的平均听阈无显著性差异（P〉0．05）。各单项识别率开机后半年与一年纵向比较,差异均有统计学意义（P〈0．001）。组间横向比较,开机半年及一年时,韵母识别能力始终优于声母、声调识别能力,差异具有统计学意义（P〈0．001）,单音节词识别能力相对弱于双音节词、三音节词识别能力,差异亦具有统计学意义（P〈0．001）;两次评估中,选择性听取能力始终落后于其他各项。结论听觉康复过程符合从声音察觉、感知再到理解的规律,对语言的理解识别也符合先简单后复杂的规律,即从音节要素到词语、再到短句。康复过程需有侧重,人工耳蜗开机后前半年需注重听觉感知能力的提高,而后半年需注重对语言理解能力的培养。     

Sweep-Frequency Tympanometry: Its Development and Diagnostic Value

This reports a newly developed tympanometric system using a sweep-frequency probe tone. For a sweep-frequency tone ranging from 220 to 2 000 Hz, measurements of sound pressure (P) and phase (Θ) were performed at ear canal pressures of 0 and -200 mm H₂0. The results were expressed as a sound pressure curve (P₀-P_-200 m decibels), a phase curve (Θ₀-Θ_-200 in degrees) and a polar curve (P₀-P_-200, Θ₀-Θ_-200) against probe tone frequency. Both the frequency at which the sound pressure curve crossed the 0-dB difference line and the peak frequency of the phase curve shifted lower than normal for ossicular disruption and higher than normal for ossicular fixation. Changes in the sound pressure curve and in the phase curve were exaggerated for ossicular disruption and limited for fixation. As the result of these, the polar curve showed an expanded type for disruption and a compressed type for fixation. A review of 220-Hz tympanograms and of the polar curves for 10 patients demonstrated that the latter permitted a better discrimination among ossicular disorders.     

Examination of the neighborhood activation theory in normal and hearing-impaired listeners

OBJECTIVE: Experiments were conducted to examine the effects of lexical information on word recognition among normal hearing listeners and individuals with sensorineural hearing loss. The lexical factors of interest were incorporated in the Neighborhood Activation Model (NAM). Central to this model is the concept that words are recognized relationally in the context of other phonemically similar words. NAM suggests that words in the mental lexicon are organized into similarity neighborhoods and the listener is required to select the target word from competing lexical items. Two structural characteristics of similarity neighborhoods that influence word recognition have been identified; "neighborhood density" or the number of phonemically similar words (neighbors) for a particular target item and "neighborhood frequency" or the average frequency of occurrence of all the items within a neighborhood. A third lexical factor, "word frequency" or the frequency of occurrence of a target word in the language, is assumed to optimize the word recognition process by biasing the system toward choosing a high frequency over a low frequency word. DESIGN: Three experiments were performed. In the initial experiments, word recognition for consonant-vowel-consonant (CVC) monosyllables was assessed in young normal hearing listeners by systematically partitioning the items into the eight possible lexical conditions that could be created by two levels of the three lexical factors, word frequency (high and low), neighborhood density (high and low), and average neighborhood frequency (high and low). Neighborhood structure and word frequency were estimated computationally using a large, on-line lexicon-based Webster's Pocket Dictionary. From this program 400 highly familiar, monosyllables were selected and partitioned into eight orthogonal lexical groups (50 words/group). The 400 words were presented randomly to normal hearing listeners in speech-shaped noise (Experiment 1) and "in quiet" (Experiment 2) as well as to an elderly group of listeners with sensorineural hearing loss in the speech-shaped noise (Experiment 3). RESULTS: The results of three experiments verified predictions of NAM in both normal hearing and hearing-impaired listeners. In each experiment, words from low density neighborhoods were recognized more accurately than those from high density neighborhoods. The presence of high frequency neighbors (average neighborhood frequency) produced poorer recognition performance than comparable conditions with low frequency neighbors. Word frequency was found to have a highly significant effect on word recognition. Lexical conditions with high word frequencies produced higher performance scores than conditions with low frequency words. CONCLUSION: The results supported the basic tenets of NAM theory and identified both neighborhood structural properties and word frequency as significant lexical factors affecting word recognition when listening in noise and "in quiet." The results of the third experiment permit extension of NAM theory to individuals with sensorineural hearing loss. Future development of speech recognition tests should allow for the effects of higher level cognitive (lexical) factors on lower level phonemic processing.