Word Recognition by Children Listening to Speech Processed into a Small Number Word Recognition by Children Listening to Speech Processed into a Small Number of Channels: Data from Normal-Hearing Children and Children with Cochlear Implants of Channels: Data from Normal-Hearing Children and Children with Cochlear Implants
Dorman, Michael F.; Loizou, Philipos C.; Kemp, Lauren L.; Iler Kirk, and Karen
Ear and Hearing . 21(6):590-596, December 2000.
Objective: The aims of this study were 1) to determine the number of channels of stimulation needed by normal-hearing adults and children to achieve a high level of word recognition and 2) to compare the performance of normal-hearing children and adults listening to speech processed into 6 to 20 channels of stimulation with the performance of children who use the Nucleus 22 cochlear implant.
Design: In E-periment 1, the words from the Multisyllabic Le-ical Neighborhood Test (MLNT) were processed into 6 to 20 channels and output as the sum of sine waves at the center frequency of the analysis bands. The signals were presented to normal-hearing adults and children for identification. In E-periment 2, the wideband recordings of the MLNT words were presented to early-implanted and late-implanted children who used the Nucleus 22 cochlear implant.
Results: E-periment 1: Normal-hearing children needed more channels of stimulation than adults to recognize words. Ten channels allowed 99% correct word recognition for adults; 12 channels allowed 92% correct word recognition for children. E-periment 2: The average level of intelligibility for both early- and late-implanted children was equivalent to that found for normal-hearing adults listening to four to si- channels of stimulation. The best intelligibility for implanted children was equivalent to that found for normal-hearing adults listening to si- channels of stimulation. The distribution of scores for early- and late-implanted children differed. Nineteen percent of the late-implanted children achieved scores below that allowed by a 6-channel processor. None of the early-implanted children fell into this category.
Conclusions: The average implanted child must deal with a signal that is significantly degraded. This is likely to prolong the period of language acquisition. The period could be significantly shortened if implants were able to deliver at least eight functional channels of stimulation. Twelve functional channels of stimulation would provide signals near the intelligibility of wideband signals in quiet.
CHILDREN SPEECH CLINIC