Mario A. Svirsky

Language Development in Profoundly Deaf Children with Cochlear Implants

Although cochlear implants improve the ability of profoundly deaf children to understand speech, critics claim that the published literature does not document even a single case of a child who has developed a linguistic system based on input from an implant. Thus, it is of clinical and scientific importance to determine whether cochlear implants facilitate the development of English language skills. The English language skills of prelingually deaf children with cochlear implants were measured before and after implantation. We found that the rate of language development after implantation exceeded that expected from unimplanted deaf children (p < .001) and was similar to that of children with normal hearing. Despite a large amount of individual variability, the best performers in the implanted group seem to be developing an oral linguistic system based largely on auditory input obtained from a cochlear implant.

Development of Language and Speech Perception in Congenitally, Profoundly Deaf Children as a Function of Age at Cochlear Implantation

Like any other surgery requiring anesthesia, cochlear implantation in the first few years of life carries potential risks, which makes it important to assess the potential benefits. This study introduces a new method to assess the effect of age at implantation on cochlear implant outcomes: developmental trajectory analysis (DTA). DTA compares curves representing change in an outcome measure over time (i.e. developmental trajectories) for two groups of children that differ along a potentially important independent variable (e.g. age at intervention). This method was used to compare language development and speech perception outcomes in children who received cochlear implants in the second, third or fourth year of life. Within this range of age at implantation, it was found that implantation before the age of 2 resulted in speech perception and language advantages that were significant both from a statistical and a practical point of view. Additionally, the present results are consistent with the existence of a ‘sensitive period’ for language development, a gradual decline in language acquisition skills as a function of age.

Enhancement of expressive language in prelingually deaf children with cochlear implants.

Expressive language skills were assessed in two groups of prelingually-deafened children using the Reynell Developmental Language Scales (RDLS). Results from a group of 89 unimplanted subjects provided cross-sectional data which suggested that profoundly deaf children without implants, on average, could only be expected to make 5 months of expressive language growth in one year. Twenty-three children who received cochlear implants made up the second group of subjects and were administered the RDLS at three intervals: preimplant, 6-, and 12-months postimplant. The scores obtained at the post-implant intervals were then compared to scores that would be predicted on the basis of maturation alone, without the implant (these predictions were formulated based on the data obtained from the unimplanted subjects). At the 12-month postimplant interval, the observed mean language score was significantly higher than the predicted score. Although the mean group data were extremely encouraging, wide inter- subject variability was observed. Although the implant subjects, as a group, were substantially delayed compared with their normal hearing peers, their rate of language growth was found to match that of hearing peers, following implantation. Thus, the gap between chronological age and language age, which normally widens over time in deaf children, remained constant. Preliminary analyses over the first 2.5 years post-implant are consistent with this trend. These results suggest that early implantation (before age 3) might be beneficial to profoundly deaf children because the language delays at the time of implantation would be much smaller.

Communication Skills in Pediatric Cochlear Implant Recipients

Detailed longitudinal studies of speech perception, speech production and language acquisition have justified a significant change in the demographics of congenitally and prelingually deaf children who receive cochlear implants. A trend toward earlier cochlear implantation has been justified by improvements in measures assessing these areas. To assess the influence of age at implantation on performance, age 5 years was used as a benchmark. Thirty-one children who received a Nucleus cochlear implant and use the SPEAK speech processing strategy and two children who received a Clarion cochlear implant and use the CIS strategy served as subjects. The subjects were divided into three groups based on age at implantation. The groups comprised children implanted before the age of 3 years (n = 14), children implanted between 3 years and 3 years 11 months (n = 11) and those implanted between 4 years and 5 years 3 months (n = 8). The children were further divided according to whether they used oral or total communication. The earlier-implanted groups demonstrated statistically significant improvements on measures of speech perception. Improvements in speech intelligibility as a function of age at implant were seen but did not reach statistical significance. The results of the present study demonstrate that early implantation promotes the acquisition of speaking and listening skills.

Children with implants can speak, but can they communicate? ☆ ☆☆ ★

English-language skills were evaluated in two groups of profoundly hearing-impaired children with the Reynell Developmental Language Scales, Revised. The first group consisted of 89 deaf children who had not received cochlear implants. The second group consisted of 23 children wearing Nucleus multichannel cochlear implants. The subjects without implants provided cross-sectional language data used to estimate the amount of language gains expected on the basis of maturation. The Reynell data from the group without implants were subjected to a regression by age. On the basis of this analysis, deaf children were predicted to make half or less of the language gains of their peers with normal hearing. Predicted language scores were then generated for the subjects with implants by using the childrens preimplant Reynell Developmental Language Scale scores. The predicted scores were then compared with actual scores achieved by the subjects with implants 6 and 12 months after implantation. Twelve months after implantation, the subjects demonstrated gains in receptive and expressive language skills that exceeded by 7 months the predictions made on the basis of maturation alone. Moreover, the average language-development rate of the subjects with implants in the first year of device use was equivalent to that of children with normal hearing. These effects were observed for children with implants using both the oral and total-communication methods.

Language Development in Deaf Infants Following Cochlear Implantation

Objective—To evaluate the benefits of cochlear implantation in infancy and compare them to those obtained in children implanted at a slightly older age.Material and Methods—Using standard language measurement tools, including the Grammatical Analysis of Elicited Language—Presentence Level (GAEL-P) and the Reynell Developmental Language Scales, progress was documented in a child who received a cochlear implant in infancy and compared to that achieved in children implanted at older ages. A new measurement tool, the Visual Habituation Procedure, was used to document early skills and the results were compared to those obtained in normal-hearing infants.Results—By the age of 2 years the subject implanted in infancy achieved scores on the GAEL-P which were nearly equivalent to those achieved at the age of 51/2 years by children implanted at later ages. Age-equivalent scores on the Reynell Developmental Language Scales were achieved by the subject implanted in infancy and the ability to discriminate speech patterns was demonstrated using the Visual Habituation Procedure.Conclusion—This report demonstrates enhanced language development in an infant who received a cochlear implant at the age of 6 months.

Auditory Learning and Adaptation after Cochlear Implantation: A Preliminary Study of Discrimination and Labeling of Vowel Sounds by Cochlear Implant Users

This study examined two possible reasons underlying longitudinal increases in vowel identification by cochlear implant users: improved labeling of vowel sounds and improved electrode discrimination. The Multidimensional Phoneme Identification (MPI) model was used to obtain ceiling estimates of vowel identification for each subject, given his/her electrode discrimination skills. Vowel identification scores were initially lower than the ceiling estimates, but they gradually approached them over the first few months post-implant. Taken together, the present results suggest that improved labeling is the main mechanism explaining post-implant increases in vowel identification.This study examined two possible reasons underlying longitudinal increases in vowel identification by cochlear implant users: improved labeling of vowel sounds and improved electrode discrimination. The Multidimensional Phoneme Identification (MPI) model was used to obtain ceiling estimates of vowel identification for each subject, given his/her electrode discrimination skills. Vowel identification scores were initially lower than the ceiling estimates, but they gradually approached them over the first few months post-implant. Taken together, the present results suggest that improved labeling is the main mechanism explaining post-implant increases in vowel identification.

Imitative consonant feature production by children with multichannel sensory aids.

Objective: To examine changes over time in consonant feature production by children with profound hearing impairments who used either the Nucleus multichannel cochlear implant or the multichannel vibrotactile aid, Tactaid 7. Design: Imitative consonant productions of children with prelingual deafness were elicited and transcribed at two intervals: 1) before receiving their respective devices (predevice interval), and 2) after an average of 1.5 yr of device use (postdevice interval). The consonant productions were analyzed in terms of the percentage of consonant features (manner, place, and voicing) produced by the child that matched the features of the examiners target. The percentage of features produced correctly was then averaged across repetitions, vowel environments, and participants within each group. Results: At the predevice interval, the cochlear implant and Tactaid 7 participants demonstrated similar imitative consonant production abilities. After an average of 1.5 yr of device use, the cochlear implant participants demonstrated significantly greater gains than did the Tactaid 7 participants for the features of voicing and place of articulation. Although the cochlear implant participants showed a trend towards better production of the consonant manner features, this difference failed to reach significance. Conclusions: The current results suggest that the use of a multichannel sensory aid yields improvements in consonant feature production. Furthermore, use of a cochlear implant appears to promote the production of consonant voicing and place features to a greater degree than does the use of a multichannel tactile aid.

Speech intelligibility of prelingually deaf children with multichannel cochlear implants.

INTRODUCTION The most obvious benefit of a cochlear implant (CI) is aid in speech perception. However, one of the major benefits of CIs is in the development of intelligible speech, something that is very difficult for congenitally profoundly deaf children. Although the assessment of speech intelligibility by naive listeners (rather than by parents or clinicians) is laborious and time-consuming, this measure has high reliability and face validity. Previous studies have demonstrated substantial increases in intelligibility by profoundly deaf children after receiving CIs.· These studies compared the intelligibility of CI users with intelligibility scores predicted for hearing aid (HA) users. Most subjects in the CI group were users of the multipeak (MPEAK) stimulation strategy rather than the state-ofthe-art strategies spectral peak (SPEAK) or Continuous Interleaved Sampler (CIS). It was found that the CI users matched the speech intelligibility of HA users, with a pure tone average (PTA) between 100 and 110 dB hearing level (HL) after 1 to 2.5 years of CI use. However, the CI users did not reach the speech intelligibility shown by HA users with more residual hearing (90 to 100 dB HL), even after 5 years of CI use.

The effects of processor strategy on the speech perception performance of pediatric nucleus multichannel cochlear implant users

Objective: The present investigation examined the speech perception skills of pediatric cochlear implant users who changed from their original speech processors and strategies to the Spectral Peak (SPEAK) strategy. Design: A within‐subjects design was used to compare individual subjects performance using the SPEAK strategy with that obtained with their previous speech strategy (F0F1F2 or Multipeak) in this retrospective study. The subjects demonstrated a wide range of perceptual abilities and had used a cochlear implant for varying lengths of time before converting to the SPEAK strategy. Results: Nine of the 11 subjects showed significant improvement on at least one of the open‐set word recognition measures, whereas two subjects showed no change on any of the open‐set measures when using the SPEAK strategy. Conclusions: The present results suggest that the majority of pediatric cochlear implant users are likely to show improved speech perception performance when converting to the new SPEAK processing strategy.