Search

Children with progressive sensorineural hearing impairment represent a special challenge to the audiologist and the otologist. These are patients with some residual auditory abilities that deteriorate with time as the hearing loss progresses. No doubt, the unnecessary implantation of an ear that significantly benefits from amplification needs to be avoided at all costs. By the same token however, there appears to be no advantage to waiting an inordinate amount of time after the loss of functional auditory abilities before recommending implantation. At times when a complete loss is predictable, implantation may be advantageous before the onset of complete auditory deprivation. Steps the clinicians should take to manage these patients effectively are briefly summarized below: Implementation of rigorous and frequent audiologic monitoring. If, for instance, a significant progressive loss of hearing has occurred over a 6-month period, resulting in a complete absence of open-set speech recognition abilities in the auditory-alone mode with appropriate hearing aids, it is probably counterproductive to wait to the point of a complete absence of aided speech detection. Implantation at a critical point in time will prevent complete auditory deprivation. Parental counseling concerning various management strategies, such as use of vibrotactile devices, changing communication skills, and issues involving cochlear implants need to be undertaken early. Parents need to be involved in every phase of the evaluation process because they are the ones who make the final decision concerning the implantation of their child. Relatively early implantation should be considered in light of what is known concerning the effects of disruption in a child's linguistic, cognitive, and emotional development resulting from complete auditory deprivation.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of this experiment was first, to compare the performance of three matched groups of experimental subjects who used either a single-channel cochlear implant, a multichannel cochlear implant, or a two-channel vibrotactile aid on a battery of speech perception measures, and second, to compare the performance of subjects with residual hearing who used hearing aids to that of the three groups of experimental subjects. The results revealed that the subjects using hearing aids achieved the highest scores on all measures. The performance of the group of multichannel implant users was significantly higher than that of the single-channel implant users on tests involving discrimination of speech features, categorization of stress patterns, closed-set identification of familiar words, and identification of common phrases with and without visual cues. The performance of the subjects using 3M/House and Tactaid II devices was similar on all tests except those requiring integration of auditory or tactile cues and visual cues, on which the 3M/House device users achieved significantly higher scores than did the Tactaid II device users.

Although a tremendous amount of information has been obtained about the benefits derived from implants and tactile aids during the last few years, many areas of research need to be addressed. Objective measures are needed to assess nerve survival in potential implant candidates, factors need to be identified that predict levels of implant performance, and extensive research needs to be conducted to identify methods to optimize fitting strategies with implants. To date, relatively few studies have examined the performance of clinical populations, especially profoundly hearing-impaired children, with sophisticated multichannel tactile aids. Further, it is not known what type of tactile transform provides the greatest improvements in performance. It appears as if learning effects extend over many years in pediatric users of implants and tactile aids, and it is crucial that longitudinal data be collected. Further, there is a need to document gains in speech perception and speech production skills when both hearing aids and tactile aids are used by profoundly hearing-impaired children who demonstrate residual hearing. As technology improves and new sensory aids become available, the need for continued research expands. Even in these early stages of investigation, both cochlear implants and tactile aids have proven effective in the rehabilitation of children and adults who are profoundly deaf.

A longitudinal study is under way to examine the speech perception and production skills of deaf children who use a single- or multi-channel cochlear implant, or a two-channel tactile aid. The speech perception data showed that the majority of subjects who achieved the highest scores on a range of measures used the multi-channel cochlear implant. The production data showed that all three types of sensory aids were effective in promoting production skills, with the cochlear implant users showing the greatest gains in this area.

This study evaluated 20 deaf adults' ability to understand connected discourse under two conditions: (a) lipreading alone (LA), and (b) lipreading plus electrical stimulation by a single-channel cochlear implant (LI). Performance was evaluated using the speech-tracking procedure, which required the deaf receiver to repeat verbatim textual material read by another individual. The reception of ongoing speech was measured in terms of the number of words repeated correctly per minute. The results revealed, on the average, a significantly higher tracking rate in the LI condition (28.6 wpm) than the LA condition (16.4 wpm). There was a significant learning effect across sessions for both conditions. Subjects who were previous hearing aid users achieved a significantly higher tracking rate in the LI condition than did subjects who had no previous experience with amplification. Significant subject differences were present as a function of condition. Sixteen of the 20 subjects achieved higher tracking rates in the LI than in the LA condition. However, 4 of these 16 subjects showed similar relative gains in both conditions and 3 showed a decrease in performance in the LA condition over time. The remaining 4 subjects showed nearly equivalent tracking rates in both conditions over time. The data suggest that the majority of subjects were able to learn to make use of the cues provided by electrical stimulation by a single-channel cochlear implant to enhance their lipreading skills, at least for highly redundant material in a communicative situation.

The subjects of this report are identical (monozygotic) twin boys who differ in auditory function. One has normal hearing; the other has a profound hearing loss bilaterally. These boys offered a rare opportunity to study the effects of hearing loss on vocal development with reasonable control over environmental and genetic factors. This initial report focuses on their vocal development over the sampled ages of 8, 12, and 15 months. Acoustic-phonetic differences in the babbling of the two boys were evident in the 8-month sample (the first recording opportunity), and some differences between them became greater over the succeeding samples at 12 and 15 months. The major differences were in the formant patterns of vocalic elements; the frequency of occurrence of fricatives, affricates, and trills; histograms of syllable type; and variation in vowel usage. The data hold implications for the early identification of infants at risk for communication disorder and for the understanding of auditory-motor processes in phonetic development during infancy.

Systematic speech training procedures were employed with a group of 20 hearing-impaired children ranging in age from 7 to 10 years. Using a primarily auditory-oral approach, the speech training program employed a hierarchical sequence in order to teach the suprasegmental patterns of English to the children. The children's performance on the speech training hierarchy was monitored on a daily basis using a checklist system. Based on their rate of progress in the development of speech skills, the children were divided into three groups post hoc: rapid, slow but steady, inordinately slow. Although the system worked well, on the average, approximately one-third of the children encountered serious difficulites at one or more levels of the hierarchy. Examination of the children's background information and audiological data revealed that those children who encountered difficulty had an extremely limited amount of residual hearing and/or problems other than a hearing handicap.

The connected discourse tracking procedure was adopted for use as a production training task for profoundly hearing-impaired children. A clinician served as the receiver and 5 children with profound hearing losses each served as the sender for 16 tracking sessions. There were individual differences among the children in their ability to convey the connected discourse to the clinician over time. The increase in comprehension of each subject's speech during the last session relative to the amount of information understood during the first session ranged from 0 to 48%. Two independent observers were used during the first and last sessions to verify the tracking results obtained by the clinician (the primary receiver). There were differences in words tracked per minute among the three receivers with the primary clinician achieving higher tracking rates than the other two. The children learned how to use discourse strategies when they were not understood and they were highly motivated by the task. The results indicate that it is feasible to incorporate the procedure in a speech training program for hearing-impaired children.

Two profoundly hearing-impaired adolescents received systematic speech training to improve their production of the vowels /i/ and /ae/. Acoustic measures of F1, F2, and duration, and listener judgements of vowel acceptability, were used to quantify vowel production before and after training. Both subjects demonstrated significant changes in their production of the two vowels at the acoustic and perceptual levels following treatment. The changes were highly individualized. For some features, significant improvement occurred posttreatment with differences between the hearing-impaired subject and a control group of subjects with normal hearing no longer present. There was a significant improvement in the acceptability of the two vowels in each subject's speech after training. Vowel duration remained unchanged in the speech of one subject whereas it increased in the speech of the other subject following training. There was a trend toward reduced token-to-token variation in the posttreatment samples. Acoustic and perceptual measures also were obtained on two vowels not directly trained in the program. Significant changes occurred in the production of these segments but some of the changes resulted in greater deviation in the post- than in the pretreatment samples.

The purpose of this study was to quantify the effect of timing errors on the intelligibility of deaf children's speech. Deviant timing patterns were corrected in the recorded speech samples of six deaf children using digital speech processing techniques. The speech waveform was modified to correct timing errors only, leaving all other aspects of the speech unchanged. The following six-stage approximation procedure was used to correct the deviant timing patterns: (1) original, unaltered utterances, (2) correction of pauses only, (3) correction of relative timing, (4) correction of absolute syllable duration, (5) correction of relative timing and pauses, and (6) correction of absolute syllable duration and pauses. Measures of speech intelligibility were obtained for the original and the computer-modified utterances. On the average, the highest intelligibility score was obtained when relative timing errors only were corrected. The correction of this type of error improved the intelligibility of both stressed and unstressed words within a phrase. Improvements in word intelligibility, which occurred when relative timing was corrected, appeared to be closely related to the number of phonemic errors present within a word. The second highest intelligibility score was obtained for the original, unaltered sentences. On the average, the intelligibility scores obtained for the other four forms of timing modification were poorer than those obtained for the original sentences. Thus, the data show that intelligibility improved, on the average, when only one type of error, relative timing, was corrected.

A speech perception hierarchy has been developed and applied to assess the influence of cochlear implants and tactile aids on the acquisition of auditory, speech, and language skills in deaf children. Encouraging improvements were noted with both types of sensory aids at the detection level. The House 3M and Nucleus cochlear implant designs appear to offer advantages over the Tactaid II in providing ancillary speech perception cues to deaf children. Preliminary observations suggest that the multichannel cochlear implant design may be superior to the single-channel coding scheme.