Speech Recognition Skills Research Articles

Early Sign Language Exposure and Cochlear Implantation Benefits.

Most children with hearing loss who receive cochlear implants (CI) learn spoken language, and parents must choose early on whether to use sign language to accompany speech at home. We address whether parents' use of sign language before and after CI positively influences auditory-only speech recognition, speech intelligibility, spoken language, and reading outcomes. Three groups of children with CIs from a nationwide database who differed in the duration of early sign language exposure provided in their homes were compared in their progress through elementary grades. The groups did not differ in demographic, auditory, or linguistic characteristics before implantation. Children without early sign language exposure achieved better speech recognition skills over the first 3 years postimplant and exhibited a statistically significant advantage in spoken language and reading near the end of elementary grades over children exposed to sign language. Over 70% of children without sign language exposure achieved age-appropriate spoken language compared with only 39% of those exposed for 3 or more years. Early speech perception predicted speech intelligibility in middle elementary grades. Children without sign language exposure produced speech that was more intelligible (mean = 70%) than those exposed to sign language (mean = 51%). This study provides the most compelling support yet available in CI literature for the benefits of spoken language input for promoting verbal development in children implanted by 3 years of age. Contrary to earlier published assertions, there was no advantage to parents' use of sign language either before or after CI.

Speech Recognition and Cognitive Skills in Bimodal Cochlear Implant Users

To examine the relation between speech recognition and cognitive skills in bimodal cochlear implant (CI) and hearing aid users. Seventeen bimodal CI users (28-74 years) were recruited to the study. Speech recognition tests were carried out in quiet and in noise. The cognitive tests employed included the Reading Span Test and the Trail Making Test (Daneman & Carpenter, 1980; Reitan, 1958, 1992), measuring working memory capacity and processing speed and executive functioning, respectively. Data were analyzed using paired-sample t tests, Pearson correlations, and partial correlations controlling for age. The results indicate that performance on some cognitive tests predicts speech recognition and that bimodal listening generates a significant improvement in speech in quiet compared to unilateral CI listening. However, the current results also suggest that bimodal listening requires different cognitive skills than does unimodal CI listening. This is likely to relate to the relative difficulty of having to integrate 2 different signals and then map the integrated signal to representations stored in the long-term memory. Even though participants obtained speech recognition benefit from bimodal listening, the results suggest that processing bimodal stimuli involves different cognitive skills than does unimodal conditions in quiet. Thus, clinically, it is important to consider this when assessing treatment outcomes.

The impact of speech rate on sentence recognition by elderly individuals

Difficulty understanding speech, particularly in situations unfavorable to communication, is a common complaint among elderly individuals. ObjectiveTo verify the variables connected to hearing loss and stimulus presentation rate and their impact on the speech recognition skills of elderly subjects in quiet and noisy environments. MethodThis case-control study included two groups of subjects (31 elderly subjects with normal hearing and 26 with hearing loss) exposed to the List of Sentences in Portuguese and the Slowed List of Sentences in Portuguese tests. Sentence recognition indices were calculated for tests done against noisy and quiet backgrounds at a normal and reduced speech rate. Data sets were submitted to statistical analysis. Resultselderly subjects from both groups had better test results when sentences were played at a slower rate. Statistically significant difference was seen for both groups when the tests were carried out on a quiet background and for the group with hearing loss when tested on a noisy background. Conclusionregardless of their peripheral hearing, the elderly subjects included in this study were more able to recognize speech when sentences were played at a slower rate against a quiet background. When sentences were played against a noisy background, the elderly subjects with hearing loss had more significant performance improvements than the ones with normal hearing when sentences were played at a slower rate.

Reconhecimento de fala em crianças usuárias de implante coclear utilizando dois diferentes processadores de fala

OBJETIVO: Estudar comparativamente a habilidade de reconhecimento de fala no silêncio e na presença de ruído competitivo em crianças usuárias de implante coclear utilizando dois diferentes processadores de fala. MÉTODOS: Foram avaliadas 26 crianças usuárias do implante coclear Nucleus 24M/24K, da Cochlear Corporation®, divididas em dois grupos de acordo com o processador de fala utilizado. O Grupo 1 foi composto por 16 crianças que faziam uso do processador de fala Sprint e o Grupo 2 foi composto por 10 crianças que faziam uso do processador de fala Freedom. Foi aplicado o Hearing in Noise Test - versão em Português/Brasil, em campo livre, na condição de silêncio e na presença de ruído competitivo. RESULTADOS: O desempenho do Grupo 2 (Freedom) foi superior ao desempenho do Grupo 1 (Sprint) em todas as condições de avaliação, sendo evidenciada diferença entre eles na condição de silêncio. CONCLUSÃO: O processador de fala apresentou influência significativa na percepção de fala de crianças usuárias dos implantes cocleares Nucleus 24K e 24M. As características de pré-processamento do som presentes no processador de fala Freedom podem ter contribuído para o melhor desempenho do Grupo 2 nos testes de percepção de fala realizados. Novos estudos são necessários para complementação destes achados.

Across-site patterns of modulation detection: relation to speech recognition.

The aim of this study was to identify across-site patterns of modulation detection thresholds (MDTs) in subjects with cochlear implants and to determine if removal of sites with the poorest MDTs from speech processor programs would result in improved speech recognition. Five hundred millisecond trains of symmetric-biphasic pulses were modulated sinusoidally at 10 Hz and presented at a rate of 900 pps using monopolar stimulation. Subjects were asked to discriminate a modulated pulse train from an unmodulated pulse train for all electrodes in quiet and in the presence of an interleaved unmodulated masker presented on the adjacent site. Across-site patterns of masked MDTs were then used to construct two 10-channel MAPs such that one MAP consisted of sites with the best masked MDTs and the other MAP consisted of sites with the worst masked MDTs. Subjects' speech recognition skills were compared when they used these two different MAPs. Results showed that MDTs were variable across sites and were elevated in the presence of a masker by various amounts across sites. Better speech recognition was observed when the processor MAP consisted of sites with best masked MDTs, suggesting that temporal modulation sensitivity has important contributions to speech recognition with a cochlear implant.

An underestimated issue: unsuspected decrease of sound processor microphone sensitivity, technical, and clinical evaluation

ObjectiveTo describe the rate of occurrence of unsuspected decrease in sensitivity of the sound processor microphone and to evaluate its effect on the patient's audiological performance in terms of reduction in speech recognition scores.DesignSpeech processor microphones were tested by connecting the speech processor acoustic monitor circuit to a hearing aid analyzer. The response curves were compared with those obtained from fully working microphones.During a 6-month investigation period, microphone response curves were measured from a group of cochlear implant recipients who had not reported any problems. Despite the absence of any subjective problem, some microphones were found to show a loss of sensitivity. Their users, aged between 4 and 67 years, were tested both with the defective and a working microphone in order to calculate the correlation between the degree of microphone failure and the decline in audiological performance.To quantify the effect of microphone failure, patients’ speech recognition skills were measured by live voice connected discourse tracking series administered in different conditions and by recorded sentences lists.ResultsA total of 120 apparently fully functioning sound processors were tested in the investigation: 33 (27.5%) were affected by a subjectively unreported sensitivity decrease. Speech-tracking scores correlated significantly with the loss of microphone sensitivity in all test conditions (r = 0.69–0.77, P < 0.05). A high degree of correlation was also found for speech audiometry tests (r = 0.70–0.73, P < 0.05). Microphone sensitivity loss affected speech recognition skills, especially without lip reading and in the presence of background noise.ConclusionThe results indicate that any reduction in sound processor microphone sensitivity causes a degree of hearing decline that negatively affects the cochlear recipient's clinical performance. Microphone faults are often unreported events, and their occurrence rate is underestimated. To establish that the microphone is providing correct input to the speech processor a standard control procedure, including technical and clinical checks, is needed in clinical practice.

Aging, Audiovisual Integration, and the Principle of Inverse Effectiveness

The purpose of this investigation was to compare the ability of young and older adults to integrate auditory and visual sentence materials under conditions of good and poor signal clarity. The principle of inverse effectiveness (PoIE), which characterizes many neuronal and behavioral phenomena related to multisensory integration, asserts that as unimodal performance declines, integration is enhanced. Thus, the PoIE predicts that both young and older adults will show enhanced integration of auditory and visual speech stimuli when these stimuli are degraded. More importantly, because older adults' unimodal speech recognition skills decline in both the auditory and visual domains, the PoIE predicts that older adults will show enhanced integration during audiovisual speech recognition relative to younger adults. This study provides a test of these predictions. Fifty-three young and 53 older adults with normal hearing completed the closed-set Build-A-Sentence test and the CUNY Sentence test in a total of eight conditions; four unimodal and four audiovisual. In the unimodal conditions, stimuli were either auditory or visual and either easier or harder to perceive; the audiovisual conditions were formed from all the combinations of the unimodal signals. The hard visual signals were created by degrading video contrast, and the hard auditory signals were created by decreasing the signal to noise ratio. Scores from the unimodal and bimodal conditions were used to compute auditory enhancement and integration enhancement measures. Contrary to the PoIE, neither the auditory enhancement nor integration enhancement measures increased when signal clarity in the auditory or visual channel of audiovisual speech stimuli was decreased, nor was either measure higher for older adults than for young adults. In audiovisual conditions with easy visual stimuli, the integration enhancement measure for older adults was equivalent to that for young adults. However, in conditions with hard visual stimuli, integration enhancement for older adults was significantly lower than that for young adults. The present findings do not support extension of the PoIE to audiovisual speech recognition. Our results are not consistent with either the prediction that integration would be enhanced under conditions of poor signal clarity or the prediction that older adults would show enhanced integration, relative to young adults. Although there is a considerable controversy with regard to the best way to measure audiovisual integration, the fact that two of the most prominent measures, auditory enhancement and integration enhancement, both yielded results inconsistent with the PoIE, strongly suggests that the integration of audiovisual speech stimuli differs in some fundamental way from the integration of other bimodal stimuli. The results also suggest that aging does not impair integration enhancement when the visual speech signal has good clarity, but may affect it when the visual speech signal has poor clarity.

Speech recognition, working memory and conversation in children with cochlear implants

This study examined the relationship between speech recognition, working memory and conversational skills in a group of 13 children/adolescents with cochlear implants (CIs) between 11 and 19 years of age. Conversational skills were assessed in a referential communication task where the participants interacted with a hearing peer of the same age and gender. The measures were the number of requests for clarification produced, time used to solve the task and the proportion of the different types of requests for clarification made by the participants with CIs. The results revealed that speech recognition correlated significantly with the general measures of conversational skills (time to solve the task and the total number of requests for clarification used). General working memory was associated with certain types of requests for clarification. The participants with better working memory capacity used more requests for confirmation of new information (i.e. made more suggestions of their own) and fewer requests for confirmation of already given information compared to the participants with poorer working memory. It thus seems as if both speech recognition and working memory contribute to conversational skills but in different ways. Copyright © 2009 John Wiley & Sons, Ltd.

Speech recognition, working memory and conversation in children with cochlear implants

Abstract in Undetermined This study examined the relationship between speech recognition, working memory and conversational skills in a group of 13 children/adolescents with cochlear implants (CIs) between 11 and 19 years of age. Conversational skills were assessed in a referential communication task where the participants interacted with a hearing peer of the same age and gender. The measures were the number of requests for clarification produced, time used to solve the task and the proportion of the different types of requests for clarification made by the participants with CIs. The results revealed that speech recognition correlated significantly with the general measures of conversational skills (time to solve the task and the total number of requests for clarification used). General working memory was associated with certain types of requests for clarification. The participants with better working memory capacity used more requests for confirmation of new information (i.e. made more suggestions of their own) and fewer requests for confirmation of already given information compared to the participants with poorer working memory. It thus seems as if both speech recognition and working memory contribute to conversational skills but in different ways. (Contains 1 figure and 2 tables.) (Less)

Training listeners to identify the sounds of speech: I. A review of past studies.

In this first section of a two-part article we offer an overview of research on listeners' abilities to learn to hear the spectral-temporal details of simple and complex sounds, both speech and non-speech. In the second article, to appear in the October issue of The Hearing Journal, we will describe a new training system based on that science that has recently completed clinical validation trials with users of hearing aids and of cochlear implants.1,2

Hearing Rehabilitation in Neurofibromatosis Type 2 Patients: Cochlear versus Auditory Brainstem Implantation

Objective: We aimed to evaluate and compare the auditory performance of neurofibromatosis type 2 (NF2) patients with bilateral total deafness fitted with cochlear or auditory brainstem implants. Patients and Methods: A retrospective case review was performed. Nine patients suffering from NF2 who underwent hearing rehabilitation by means of cochlear (4 patients) or auditory brainstem (5 patients) implantation participated in the study. Postoperative auditory performance was assessed using closed- and open-set tests. Results: In the group of patients fitted with a cochlear implant, 3 subjects achieved open-set speech recognition abilities comparable to those of standard adult postlingual implant patients; the remaining patient scored 0% in all open-set format tests, reporting benefits only in environmental sound detection and lip-reading. Among the 5 patients who underwent auditory brainstem implantation, 1 reached good open-set speech recognition skills, scoring 70% in the common phrases comprehension test, and she was able to communicate on the telephone. Two other patients achieved open-set speech understanding (respectively, 33 and 41% in the common phrases comprehension test), reporting daily use of their device. The remaining 2 patients did not achieve any level of open-set speech perception, obtaining only improved access to environmental sound and lip-reading skills. Conclusions: Our study confirmed literature data reporting that cochlear implantation may offer open-set speech communication in NF2 patients. In this small cohort, cochlear implant patients performed better than auditory brainstem implant patients, even if variability in auditory performance was observed with both devices. More studies are needed in order to clarify the role and reliability of electrophysiological tests in predicting the residual functionality of the cochlear nerve after tumor removal.

Effects of open-set and closed-set task demands on spoken word recognition.

Closed-set tests of spoken word recognition are frequently used in clinical settings to assess the speech discrimination skills of hearing-impaired listeners, particularly children. Speech scientists have reported robust effects of lexical competition and talker variability in open-set tasks but not closed-set tasks, suggesting that closed-set tests of spoken word recognition may not be valid assessments of speech recognition skills. The goal of the current study was to explore some of the task demands that might account for this fundamental difference between open-set and closed-set tasks. In a series of four experiments, we manipulated the number and nature of the response alternatives. Results revealed that as more highly confusable foils were added to the response alternatives, lexical competition and talker variability effects emerged in closed-set tests of spoken word recognition. These results demonstrate a close coupling between task demands and lexical competition effects in lexical access and spoken word recognition processes.

Cochlear implantation for adolescents and adults with prelinguistic deafness.

Previous studies have suggested that individuals with long-term prelinguistic deafness who receive cochlear implants show little improvement in speech recognition skills. The purpose of this study was to examine the auditory functioning of individuals with prelinguistic deafness who received cochlear implants after the age of 12. A retrospective study of open-set speech recognition was undertaken for 15 patients (adolescents and adults) with prelinguistic deafness who underwent implantation in the Ottawa Cochlear Implant Program. The results of open-set speech perception tests, both words and sentences, were reviewed to assess auditory functioning after implantation. Qualitative data using the Performance Inventory for Profound and Severe Loss questionnaire were also collected for the adults. The results of this study indicate that individuals with long-term prelinguistic deafness can achieve significant open-set speech understanding with a cochlear implant, although there is a wide range of performance across patients. The results ranged from 0% to 74% for words and 0% to 98% for sentences.

Investigation of the effects of temporal and spatial interactions on speech-recognition skills in cochlear-implant subjects.

Forward masking was investigated as a measure of spectral and temporal interactions. Such interactions may adversely affect speech recognition in cochlear-implant subjects. Seven subjects, implanted with the Nucleus 22 device, performed a forward-masking task. They also performed an electrode-discrimination task in order to measure spectral interactions without temporal interactions. Correlation analysis indicated a significant relationship between data obtained in the two tasks (p < 0.1). The two tasks were also correlated with the subjects' scores from five measures of speech recognition. Forward masking and electrode discrimination were strongly correlated with measures requiring consonant and phoneme recognition, respectively. These results indicate that the relationship between forward masking and speech recognition may be due, in part, to a lack of spectral resolution. The data also indicate that consonants may be more readily masked than vowels. Forward-masking data measured for all clinically programmed electrodes in three of the seven subjects were used with a model of the spectral maxima sound processor (SMSP) to estimate the number of electrodes stimulated during a consonant that might be masked by prior presentation of a vowel. These results suggest that temporal interactions across electrodes may be a factor in speech-recognition abilities of some cochlear-implant subjects.

Measures of auditory-visual integration in nonsense syllables and sentences.

For all but the most profoundly hearing-impaired (HI) individuals, auditory-visual (AV) speech has been shown consistently to afford more accurate recognition than auditory (A) or visual (V) speech. However, the amount of AV benefit achieved (i.e., the superiority of AV performance in relation to unimodal performance) can differ widely across HI individuals. To begin to explain these individual differences, several factors need to be considered. The most obvious of these are deficient A and V speech recognition skills. However, large differences in individuals' AV recognition scores persist even when unimodal skill levels are taken into account. These remaining differences might be attributable to differing efficiency in the operation of a perceptual process that integrates A and V speech information. There is at present no accepted measure of the putative integration process. In this study, several possible integration measures are compared using both congruent and discrepant AV nonsense syllable and sentence recognition tasks. Correlations were tested among the integration measures, and between each integration measure and independent measures of AV benefit for nonsense syllables and sentences in noise. Integration measures derived from tests using nonsense syllables were significantly correlated with each other; on these measures, HI subjects show generally high levels of integration ability. Integration measures derived from sentence recognition tests were also significantly correlated with each other, but were not significantly correlated with the measures derived from nonsense syllable tests. Similarly, the measures of AV benefit based on nonsense syllable recognition tests were found not to be significantly correlated with the benefit measures based on tests involving sentence materials. Finally, there were significant correlations between AV integration and benefit measures derived from the same class of speech materials, but nonsignificant correlations between integration and benefit measures derived from different classes of materials. These results suggest that the perceptual processes underlying AV benefit and the integration of A and V speech information might not operate in the same way on nonsense syllable and sentence input.

Speech perception abilities of adult and pediatric Nucleus implant recipients using the Spectral Peak (SPEAK) coding strategy

A series of 73 postlinguistically deafened adults and 34 prelinguistically deafened children were evaluated with the Spectral Peak (SPEAK) coding strategy of the Nucleus 22-channel cochlear implant. The adults who received consecutive implants demonstrated rapid acquisition of open-set speech recognition skills in the initial postoperative period. Group mean sentence recognition improved to 53.5% ( n = 52) after 2 weeks, 62.1% ( n = 55) after 1 month, 69.8% ( n = 57) after 3 months, and 74.4% ( n = 42) after 6 months of use. At the 6-month evaluation interval, 43% of subjects scored greater than 90% on sound-alone sentence recognition in quiet and only one patient (2.4%) scored less than 10%. Mean monosyllabic word recognition was 35.6% after 6 months of use. The 34 prelinguistically deafened children were converted from the Multipeak strategy to Spectral Peak strategy at four large pediatric implant centers. After 6 months of using the new coding strategy, the children demonstrated significant improvements in their speech perception abilities. (Otolaryngol Head Neck Surg 1997;117:236-42.)

Comparison of multichannel tactile AIDS and multichannel cochlear implants in children with profound hearing impairments: Miyamoto R.T.; Robbing A.M.; Osberger M.J.; Todds S.L.; Riley A.I.; Kirk K.I.Am. J. Otol. (USA) (1995) 16/1 (8–13)

Speech perception skills of prelingually deafened children who used the multichannel Tactaid 7 (n = 10) were compared to those of a matched group of children who used the Nucleus 22 channel cochlear implant (n = 10). Group scores were compared on a closed-set test of word recognition and on an open-set test of phrase recognition in the pre-device condition and at a post-device interval after an average of 1.5 years of multichannel device use. The results revealed that the scores of the implant users improved significantly between the pre- and post-device intervals on all measures. Moreover, the scores of the implant users were significantly higher than those of the tactile aid users on all measures. In contrast, the scores of the tactile aid users showed negligible change over time, except on a test that evaluated open-set recognition of phrases with both auditory and visual cues. The results suggest that children can learn to recognize words and understand speech without lipreading with a multichannel implant, whereas children who used the multichannel tactile aid demonstrate limited speech recognition skills only if auditory/tactile cues are combined with lipreading.

Measures of auditory‐visual integration

The easiest and most effective way to improve speech recognition for hearing‐impaired individuals, or for normal‐hearing individuals listening in noisy or reverberant environments, is to have them watch the talker’s face. Auditory‐visual (AV) speech recognition has been shown consistently to be better than either hearing alone or speechreading alone for all but the most profoundly hearing‐impaired individuals. When AV recognition is less than perfect, several factors need to be considered. The most obvious of these are poor auditory (A) and poor visual (V) speech recognition skills. However, even when differences in unimodal skill levels are taken into account, differences among individual AV recognition scores persist. At least part of these individual differences may be attributable to differing abilities to integrate A and V cues. Unfortunately, there is no widely accepted measure of AV integration ability. Recent models of AV integration offer a quantitative means for estimating individual integration abilities for phoneme recognition. In this study, we compare several possible integration measures, along with model predictions, using both congruent and discrepant AV phoneme and sentence recognition tasks. The focus of this talk will address the need for independent measures of AV integration for individual subjects. [Work supported by NIH Grant DC00792.]

Comparison of the FOF2 and FOF1F2 Processing Strategies for the Cochlear Corporation Cochlear Implant

In April 1985, an updated processing strategy became available for the Cochlear Corporation Nucleus cochlear implant. Whereas the original strategy codes only fundamental frequency, amplitude, and information in the second formant region, the newer strategy also codes frequencies in the first formant region. This investigation evaluated the speech recognition skills of five subjects who were experienced with both designs. On average, the addition of first formant information improved word identification in an audition-only condition and improved spondee recognition in noise. Scores for the NU 6 Monosyllabic Word Test and the Sentence Test Without Context improved from 8% (2-12%) to 28% words correct (10-42%), and from 31% (10-45%) to 64% words correct (39-84%), respectively. Scores for the Four-Choice Spondee Test in noise improved from 37% (25-50%) to 75% (45-90%). The percent correct scores for the Iowa 14-Item Consonant Confusion Test in an audition-only and vision-plus-audition condition did not vary with the change in processing strategy. However, an information transfer analysis performed on the responses to the consonant test in a vision-only and a vision-plus-audition condition suggested that the newer strategy enhances the transmission of the voicing, duration, and envelope features.