A comparison of speech discrimination with cochlear implants and tactile aids

This study investigates patterns of speech discrimination in profoundly hearing-impaired children who have received cochlear implants or tactile aids. The change/no change procedure was used to assess speech discrimination in these children. Three groups of subjects were tested: the first group used 3M/House single-channel cochlear implants; the second group used Nucleus 22-channel cochlear implants; and the third group used two-channel Tactaid II+ vibrotactile aids. Nine contrasts were constructed that assessed discrimination of suprasegmental and segmental speech features. Subjects were presented with stimulus trials in which stimuli changed during the trial or in which stimuli remained the same. Hits, misses, false alarms, and correct rejections were tallied and d' values were calculated for individual subjects for each contrast. Results indicated that different patterns of speech discrimination are provided by the three sensory prosthetic devices. For all contrasts, mean discrimination performance with the Nucleus device was better than that observed for the other two devices, despite the shorter duration of subject experience with this cochlear implant. In addition, interactions between device and speech contrast were not observed. Examination of individual subject performance revealed that each device group had a distribution of good to poor performers. The results suggest that the change/no change procedure is able to provide information regarding speech perception through sensory prosthetic devices despite existing differences in vocabulary and language skills of subjects.