Effect of training on word-recognition performance in noise for young normal-hearing and older hearing-impaired listeners

OBJECTIVE: The objective of this study was to evaluate the effectiveness of a training program for hearing-impaired listeners to improve their speech-recognition performance within a background noise when listening to amplified speech. Both noise-masked young normal-hearing listeners, used to model the performance of elderly hearing-impaired listeners, and a group of elderly hearing-impaired listeners participated in the study. Of particular interest was whether training on an isolated word list presented by a standardized talker can generalize to everyday speech communication across novel talkers. DESIGN: Word-recognition performance was measured for both young normal-hearing (n = 16) and older hearing-impaired (n = 7) adults. Listeners were trained on a set of 75 monosyllabic words spoken by a single female talker over a 9- to 14-day period. Performance for the familiar (trained) talker was measured before and after training in both open-set and closed-set response conditions. Performance on the trained words of the familiar talker were then compared with those same words spoken by three novel talkers and to performance on a second set of untrained words presented by both the familiar and unfamiliar talkers. The hearing-impaired listeners returned 6 mo after their initial training to examine retention of the trained words as well as their ability to transfer any knowledge gained from word training to sentences containing both trained and untrained words. RESULTS: Both young normal-hearing and older hearing-impaired listeners performed significantly better on the word list in which they were trained versus a second untrained list presented by the same talker. Improvements on the untrained words were small but significant, indicating some generalization to novel words. The large increase in performance on the trained words, however, was maintained across novel talkers, pointing to the listener's greater focus on lexical memorization of the words rather than a focus on talker-specific acoustic characteristics. On return in 6 mo, listeners performed significantly better on the trained words relative to their initial baseline performance. Although the listeners performed significantly better on trained versus untrained words in isolation, once the trained words were embedded in sentences, no improvement in recognition over untrained words within the same sentences was shown. CONCLUSIONS: Older hearing-impaired listeners were able to significantly improve their word-recognition abilities through training with one talker and to the same degree as young normal-hearing listeners. The improved performance was maintained across talkers and across time. This might imply that training a listener using a standardized list and talker may still provide benefit when these same words are presented by novel talkers outside the clinic. However, training on isolated words was not sufficient to transfer to fluent speech for the specific sentence materials used within this study. Further investigation is needed regarding approaches to improve a hearing aid user's speech understanding in everyday communication situations.     

语前聋儿童佩戴助听器后塞音发音特点

目的分析听力障碍患儿佩戴助听器后塞音的发音特点。方法以佩戴助听器的语前聋患儿30例(助听器组)和健听儿童30例(健听组)为研究对象,年龄3~6岁(分为3~、4~、5~6岁组,每组2类儿童各10例),日常均使用汉语普通话交流,具备一定的发音能力。以塞音词表进行测试,分析两组儿童塞音(/b/、/d/、/g/、/p/、/t/、/k/)的发音正确率和错误类型,分析不同生理年龄、助听时间与发音正确率的关系。结果助听器组儿童塞音发音的正确率从高到低为/b/>/d/>/g/>/k/>/t/>/p/,健听组儿童塞音发音的正确率从高到低依次为/b/>/g/>/k/>/p/>/d/>/t/;健听组儿童塞音/b/、/g/、/k/、/t/、/p/的正确率显著高于助听器组儿童(P<0.05)。助听组儿童发音错误规律包括:①发音方法相同的音互相替代,如不送气塞音的互相替代和送气塞音的互相替代;②发音部位相同的音互相替代;③发音方法和发音部位不同的替代,如:塞音擦音化,塞音塞擦音化,不送气化。4~、5~6岁组听障儿童塞音/g/、/p/、/k/发音的正确率明显高于3~岁组(P<0.05),助听器佩戴时间大于2年的听障儿童塞音/p/、/t/发音的正确率明显高于小于2年的儿童(P<0.05)。结论听障儿童塞音发音清晰度落后于健听组儿童,生理年龄、听觉干预的时间对听障儿童部分塞音发音的正确率有影响,需进行积极的干预和有针对性的康复训练。     

Effect of stimulus bandwidth on auditory skills in normal-hearing and hearing-impaired children

OBJECTIVE: Previous studies from our laboratory have shown that a restricted stimulus bandwidth can have a negative effect upon the perception of the phonemes /s/ and /z/, which serve multiple linguistic functions in the English language. These findings may have important implications for the development of speech and language in young children with hearing loss because the bandwidth of current hearing aids generally is restricted to 6 to 7 kHz. The primary goal of the current study was to expand our previous work to examine the effects of stimulus bandwidth on a wide range of speech materials, to include a variety of auditory-related tasks, and to include the effects of background noise. DESIGN: Thirty-two children with normal hearing and 24 children with sensorineural hearing loss (7 to 14 yr) participated in this study. To assess the effects of stimulus bandwidth, four different auditory tasks were used: 1) nonsense syllable perception, 2) word recognition, 3) novel-word learning, and 4) listening effort. Auditory stimuli recorded by a female talker were low-pass filtered at 5 and 10 kHz and presented in noise. RESULTS: For the children with normal hearing, significant bandwidth effects were observed for the perception of nonsense syllables and for words but not for novel-word learning or listening effort. In the 10-kHz bandwidth condition, children with hearing loss showed significant improvements for monosyllabic words but not for nonsense syllables, novel-word learning, or listening effort. Further examination, however, revealed marked improvements for the perception of specific phonemes. For example, bandwidth effects for the perception of /s/ and /z/ were not only significant but much greater than that seen in the group with normal hearing. CONCLUSIONS: The current results are consistent with previous studies that have shown that a restricted stimulus bandwidth can negatively affect the perception of /s/ and /z/ spoken by female talkers. Given the importance of these phonemes in the English language and the tendency of early caregivers to be female, an inability to perceive these sounds correctly may have a negative impact on both phonological and morphological development.     

声场中记录的听性稳态助听反应阈与行为测试助听听阈的相关性

目的 应用多频听觉稳态反应(ASSR)Chirp刺激信号在声场中测试助听反应阈,观察其阈值与行为测试助听听阈的相关性,探讨多频听觉稳态反应Chirp刺激信号声场测试评估助听器补偿效果的临床意义.方法 选取22例(39耳)重度感音神经性听力损失、已配戴助听器的患儿(听障组)和16例(32耳)听力正常儿童(对照组)为研究对象.应用国际听力Eclipse EP25型多频稳态诱发电位仪及美国GSI-61型听力计,分别对听障组在声场中使用两种仪器测试助听听阈;对对照组进行裸耳行为听阈与声场中听觉稳态反应阈测试.结果 在0.5、1、2、4 kHz处,听障组ASSR助听反应阈与行为助听听阈的相关系数分别为0.65、0.68、0.77和0.82,P值均<0.01,显示两种测试结果有相关性;对照组裸耳行为听阈与声场中记录的听觉稳态反应阈在0.5、1、2、4 kHz配对t检验均呈显著差异(P<0.01),ASSR声场反应阈高于行为听阈20～30 dB HL.结论 应用多频听觉稳态反应Chirp刺激信号声场测试进行助听器补偿效果评估在临床上具有可行性.     

Rapid word-learning in normal-hearing and hearing-impaired children: effects of age, receptive vocabulary, and high-frequency amplification

OBJECTIVE: This study examined rapid word-learning in 5- to 14-year-old children with normal and impaired hearing. The effects of age and receptive vocabulary were examined as well as those of high-frequency amplification. Novel words were low-pass filtered at 4 kHz (typical of current amplification devices) and at 9 kHz. It was hypothesized that (1) the children with normal hearing would learn more words than the children with hearing loss, (2) word-learning would increase with age and receptive vocabulary for both groups, and (3) both groups would benefit from a broader frequency bandwidth. DESIGN: Sixty children with normal hearing and 37 children with moderate sensorineural hearing losses participated in this study. Each child viewed a 4-minute animated slideshow containing 8 nonsense words created using the 24 English consonant phonemes (3 consonants per word). Each word was repeated 3 times. Half of the 8 words were low-pass filtered at 4 kHz and half were filtered at 9 kHz. After viewing the story twice, each child was asked to identify the words from among pictures in the slide show. Before testing, a measure of current receptive vocabulary was obtained using the Peabody Picture Vocabulary Test (PPVT-III). RESULTS: The PPVT-III scores of the hearing-impaired children were consistently poorer than those of the normal-hearing children across the age range tested. A similar pattern of results was observed for word-learning in that the performance of the hearing-impaired children was significantly poorer than that of the normal-hearing children. Further analysis of the PPVT and word-learning scores suggested that although word-learning was reduced in the hearing-impaired children, their performance was consistent with their receptive vocabularies. Additionally, no correlation was found between overall performance and the age of identification, age of amplification, or years of amplification in the children with hearing loss. Results also revealed a small increase in performance for both groups in the extended bandwidth condition but the difference was not significant at the traditional p = 0.05 level. CONCLUSIONS: The ability to learn words rapidly appears to be poorer in children with hearing loss over a wide range of ages. These results coincide with the consistently poorer receptive vocabularies for these children. Neither the word-learning or receptive-vocabulary measures were related to the amplification histories of these children. Finally, providing an extended high-frequency bandwidth did not significantly improve rapid word-learning for either group with these stimuli.     

听障儿童与健听儿童工作记忆的比较研究

目的 研究听障儿童与健听儿童在言语工作记忆和视空工作记忆方面的差异.方法 采用评估言语工作记忆和视空工作记忆的测验分别对听障组30例儿童和健听组30例儿童进行测试,对结果进行对比分析.结果 两组工作记忆结果有差异,健听组的言语工作记忆广度优于听障组(P＜0.05),而听障组的视空工作记忆广度优于健听组(P＜0.05);健听组的言语工作记忆广度优于其视空工作记忆广度(P＜0.05),听障组的视空工作记忆广度优于其言语工作记忆广度(P＜0.05);听障组在工作记忆任务中的提取速度并不都慢于健听组.结论 健听儿童言语工作记忆能力较强,听障儿童的视空工作记忆广度有较强的优势;在处理视空工作任务时,听障儿童未损伤通道中有较高的加工效率.     

Intelligibility of modified speech for young listeners with normal and impaired hearing.

Exposure to modified speech has been shown to benefit children with language-learning impairments with respect to their language skills (M. M. Merzenich et al., 1998; P. Tallal et al., 1996). In the study by Tallal and colleagues, the speech modification consisted of both slowing down and amplifying fast, transitional elements of speech. In this study, we examined whether the benefits of modified speech could be extended to provide intelligibility improvements for children with severe-to-profound hearing impairment who wear sensory aids. In addition, the separate effects on intelligibility of slowing down and amplifying speech were evaluated. Two groups of listeners were employed: 8 severe-to-profoundly hearing-impaired children and 5 children with normal hearing. Four speech-processing conditions were tested: (1) natural, unprocessed speech; (2) envelope-amplified speech; (3) slowed speech; and (4) both slowed and envelope-amplified speech. For each condition, three types of speech materials were used: words in sentences, isolated words, and syllable contrasts. To degrade the performance of the normal-hearing children, all testing was completed with a noise background. Results from the hearing-impaired children showed that all varieties of modified speech yielded either equivalent or poorer intelligibility than unprocessed speech. For words in sentences and isolated words, the slowing-down of speech had no effect on intelligibility scores whereas envelope amplification, both alone and combined with slowing-down, yielded significantly lower scores. Intelligibility results from normal-hearing children listening in noise were somewhat similar to those from hearing-impaired children. For isolated words, the slowing-down of speech had no effect on intelligibility whereas envelope amplification degraded intelligibility. For both subject groups, speech processing had no statistically significant effect on syllable discrimination. In summary, without extensive exposure to the speech processing conditions, children with impaired hearing and children with normal hearing listening in noise received no intelligibility advantage from either slowed speech or envelope-amplified speech.     

Discrimination of release time constants in hearing-aid compressors

We examined the ability of twenty-five hearing-impaired and eight normal-hearing listeners to discriminate between release time constants used for compression in hearing aids. The compressor was a standard three-channel system. The stimuli were normal and 'vocoded' sentences from a male and female database. In agreement with other studies looking at different outcomes, performance varied greatly across individuals. This variation was greater in hearing-impaired listeners, for whom the discriminability of a release time of 5 ms from one of 5000 ms (with the attack time fixed at 5 ms) ranged from chance to perfect. This variability was not significantly related to hearing impairment nor to individuals' compression ratios.     

Discrimination of release time constants in hearing-aid compressors

We examined the ability of twenty-five hearing-impaired and eight normal-hearing listeners to discriminate between release time constants used for compression in hearing aids. The compressor was a standard three-channel system. The stimuli were normal and ‘vocoded’ sentences from a male and female database. In agreement with other studies looking at different outcomes, performance varied greatly across individuals. This variation was greater in hearing-impaired listeners, for whom the discriminability of a release time of 5 ms from one of 5000 ms (with the attack time fixed at 5 ms) ranged from chance to perfect. This variability was not significantly related to hearing impairment nor to individuals’ compression ratios.     

Lexical and talker effects on word recognition among native and non-native listeners with normal and impaired hearing.

Evidence suggests that word recognition depends on numerous talker-, listener-, and stimulus-related characteristics. The current study examined the effects of talker variability and lexical difficulty on spoken-word recognition among four groups of listeners: native listeners with normal hearing or hearing impairment (moderate sensorineural hearing loss) and non-native listeners with normal hearing or hearing impairment. The ability of listeners to accommodate trial-to-trial variations in talkers' voice was assessed by comparing recognition scores for a single-talker condition to those obtained in a multiple-talker condition. Lexical difficulty was assessed by comparing word-recognition performance between lexically "easy" and "hard" words as determined by frequency of occurrence in language and the structural characteristics of similarity neighborhoods formalized in the Neighborhood Activation Model. An up-down adaptive procedure was used to determine the sound pressure level for 50% performance. Non-native listeners in both normal-hearing and hearing-impaired groups required greater intensity for equal intelligibility than the native normal-hearing and hearing-impaired listeners. Results, however, showed significant effects of talker variability and lexical difficulty for the four groups. Structural equation modeling demonstrated that an audibility factor accounts for 2-3 times more variance in performance than does a linguistic-familiarity factor. However, the linguistic-familiarity factor is also essential to the model fit. The results demonstrated effects of talker variability and lexical difficulty on word recognition for both native and nonnative listeners with normal or impaired hearing. The results indicate that linguistic and indexical factors should be considered in the development of speech-recognition tests.     

听觉经验及康复时间对听障儿童语言发展的影响

目的：本研究探讨学语初期听障儿童的听觉年龄与接受听觉口语法治疗的时间对语言发展的影响。方法选取台湾雅文儿童听语文教基金会听障个案18名,听觉年龄为8～16个月,以华语婴幼儿沟通发展量表婴儿版测验其语言能力,与相同听觉年龄的健听儿童常模成绩进行比较,预测分析听觉年龄和听觉口语法治疗时间对语言测验成绩的影响。结果听障儿童词汇理解与相同听觉年龄的健听儿童没有差异（P〉0.05）,但词汇表达显著落后于相同听觉年龄健听儿童。听障儿童早期及晚期手势沟通能力比相同听觉年龄健听儿童表现优异。此外,听障儿童的听觉年龄及康复时间亦能有效预测其词汇理解及晚期手势沟通的表现。结论学语初期听障儿童接受与健听儿童相同时间的听觉和语言刺激,其词汇理解发展速度与健听儿童无差异。听障儿童早期及晚期手势沟通能力皆优于健听儿童,且词汇理解和晚期手势沟通的表现随听觉口语法治疗时间的增加而上升,表明听觉口语法治疗在听障儿童学语初期的效果首先反映在词汇理解和晚期沟通手势上。     

Recognition of lexically controlled words and sentences by children with normal hearing and children with cochlear implants

OBJECTIVE: The purpose of this study was to investigate the combined lexical effects of word frequency and neighborhood density (acoustic-phonetic similarity) on the recognition of words spoken in isolation and words spoken in sentences for children with normal hearing and children with cochlear implants. DESIGN: Lexically controlled sentences were created from a subset of words obtained from the spoken vocabulary of children between the ages of 3 and 5 yr. Two sentence lists were generated, applying the definitions and procedures of Kirk, Pisoni, and Osberger (1995) in accordance with the Neighborhood Activation Model ( Luce, 1986; Luce & Pisoni, 1998). One list was composed of lexically "easy" words (those high in frequency of occurrence but phonemically dissimilar to other words) and the other list was composed of lexically "hard" words (those low in frequency of occurrence but phonemically similar to other words). Each list consisted of five practice and 20 test sentences that were syntactically correct but semantically neutral (low in predictability). Three key words were used in constructing each of the 5- to 7-word sentences, resulting in 15 practice and 60 key words per test list. In the first of three experiments, 48 normal-hearing children between the ages of 5 and 12 yr were asked to repeat the words and sentences at one of six presentation levels to establish performance-intensity functions. In the second experiment, 12 normal-hearing children between the ages of 5 and 14 yr repeated the words and sentences under spectrally degraded conditions. Twelve children with cochlear implants ages 5 to 14 yr repeated the unprocessed stimuli in a third experiment. RESULTS: The lexically easy stimuli were recognized with greater accuracy than the lexically hard stimuli for the children tested in all three experiments. Sentence scores were significantly higher than word scores for the normal-hearing children (Experiments 1 and 2) and nine high-performing children with cochlear implants (Experiment 3). Word scores were higher than sentence scores for the three low-performing children with cochlear implants. There was a statistically significant relationship between chronological age and sentence score for the normal-hearing children listening under spectrally degraded conditions. For the children with cochlear implants, the relationship between language quotient and sentence and word scores was statistically significant. CONCLUSION: Sensitivity to the combined lexical properties of word frequency and neighborhood density was evident both for words and sentences. Lexically easy stimuli were recognized with greater accuracy than lexically hard stimuli across groups, affirming the robustness of this effect and verifying that words were being organized in relation to the frequency and acoustic-phonetic properties of other words. Syntactic context facilitated word recognition for the children with normal hearing and the high-performing implant group. The three low-performing children with cochlear implants recognized words more accurately than sentences, reflecting limitations in linguistic and cognitive capacity.     

3～5岁听障儿童与健听儿童言语清晰度的比较研究

目的探讨3～5岁听障儿童与健听儿童言语清晰度的差异,为听障儿童康复训练提供参考依据。方法以黄昭鸣一韩知娟词表为测试材料,分别测试3～5岁听障儿童114名和健听儿童36名的言语清晰度得分,并进行对比研究。结果①性别和年龄的差异无统计学意义（P〉0．05）;②儿童类型的差异有统计学意义（P〈0．05）,听障儿童在3～5岁3个年龄段的言语清晰度均显著低于健听儿童;③两组儿童声母清晰度和韵母清晰度差异均有极显著统计学意义（P〈0．01）,声调清晰度差异存在显著统计学意义（P〈0．05）。结论3～5岁听障儿童的言语清晰度明显落后于同龄健听儿童,且以声母和韵母的差异最为突出,应重视对听障儿童的言语清晰度训练。     

Recognition of synthetic speech by hearing-impaired elderly listeners.

The Modified Rhyme Test (MRT), recorded using natural speech and two forms of synthetic speech, DECtalk and Votrax, was used to measure both open-set and closed-set speech-recognition performance. Performance of hearing-impaired elderly listeners was compared to two groups of young normal-hearing adults, one listening in quiet, and the other listening in a background of spectrally shaped noise designed to simulate the peripheral hearing loss of the elderly. Votrax synthetic speech yielded significant decrements in speech recognition compared to either natural or DECtalk synthetic speech for all three subject groups. There were no differences in performance between natural speech and DECtalk speech for the elderly hearing-impaired listeners or the young listeners with simulated hearing loss. The normal-hearing young adults listening in quiet out-performed both of the other groups, but there were no differences in performance between the young listeners with simulated hearing loss and the elderly hearing-impaired listeners. When the closed-set identification of synthetic speech was compared to its open-set recognition, the hearing-impaired elderly gained as much from the reduction in stimulus/response uncertainty as the two younger groups. Finally, among the elderly hearing-impaired listeners, speech-recognition performance was correlated negatively with hearing sensitivity, but scores were correlated positively among the different talker conditions. Those listeners with the greatest hearing loss had the most difficulty understanding speech and those having the most trouble understanding natural speech also had the greatest difficulty with synthetic speech.     

Auditory-visual perception of speech.

Hearing-impaired persons usually perceive speech by watching the face of the talker while listening through a hearing aid. Normal-hearing persons also tend to rely on visual cues, especially when they communicate in noisy or reverberant environments. Numerous clinical and laboratory studies on the auditory-visual performance of normal-hearing and hearing-impaired children and adults demonstrate that combined auditory-visual perception is superior to perception through either audition or vision alone. This paper reviews these studies and provides a rationale for routine evaluation of auditory-visual speech perception in audiology clinics.     

Steady state responses to multiple amplitude-modulated tones: an optimized method to test frequency-specific thresholds in hearing-impaired children and normal-hearing subjects.

OBJECTIVE: To evaluate, using statistical methods, the usefulness of the binaural multiple frequency auditory steady state responses (MF SSRs) for objective, frequency-specific audiometry in a large sample of hearing-impaired children and normal-hearing subjects. DESIGN: The MF SSRs were recorded in a sample of 43 hearing-impaired children (86 ears) and 40 normal-hearing young adults (80 ears). Simultaneous carrier tones (0.5, 1, 2, and 4 kHz) modulated in amplitude at different rates (77 to 105 Hz) were presented binaurally (TDH 49 earphones) at variable intensities (110 to 20 dB SPL). For each subject the response thresholds (RTHs) at 0.5, 1, 2, and 4 kHz, were determined automatically (F test) and compared with the corresponding behavioral thresholds (BTHs). RESULTS: In the normal-hearing subjects, RTHs were detectable, on average, between 11 and 15 dB above the BTH. These differences were significantly smaller in the hearing-impaired (5 to 13 dB). Also a close correspondence was found between the subjective and objective audiogram curves in both groups. The within subject Spearman correlation coefficients calculated between the two curves, were in most cases above the significance cut off point (p < 0.05). Also in 1-way repeated measures analysis of variance, the overall error in the estimation of the audiogram (vector across frequency of absolute distances between the curves) did not differ significantly from zero. CONCLUSIONS: The binaural MF SSR was proven to be a valid technique for the estimation of an objective audiogram, in a large sample of hearing-impaired children and normal-hearing subjects. With this method, frequency-specific thresholds at 0.5, 1, 2, and 4 kHz could be determined in all subjects (and both ears) with no appreciable loss in accuracy and a considerable reduction in testing time (average recording time = 21 minutes) when compared with other frequency-specific techniques.     

Reliability in warble-tone sound field audiometry

Test-retest reliability of sound field audiometry has been evaluated by means of repeated determinations of hearing threshold levels for frequency-modulated tones on normal-hearing and hearing-impaired subjects. Two modulation frequencies, 5 and 20 Hz, and two frequency deviations, 4 and 25%, were used, with centre frequencies in the range from 250 to 8,000 Hz. No significant influence on the standard deviations for test-retest differences was found for any of the three parameters studied: modulation frequency, frequency deviation, and normal versus impaired hearing in the listeners. The standard deviation values obtained were smaller than those previously obtained for regular pure-tone threshold audiometry using headphones. They indicate a test-retest reliability allowing functional gain measurements of hearing aids on the real ear to be performed at least as accurately as insertion gain measurements at frequencies above 2 kHz. In the hearing-impaired listeners, some influence was found from modulation frequency and frequency deviation on the sound field hearing threshold levels obtained.