Perceptual Ratings of Nonword Repetitions by Deaf Children after Cochlear Implantation: Correlations with Measures of Speech, Language and Working Memory

Seventy-six profoundly deaf children with cochlear implants completed a nonword repetition task. The children were presented with 20 nonword auditory patterns over a loudspeaker and were asked to repeat them aloud to the experimenter. All of the children were deaf before the age of 36 months. At the time of testing the children were between 8 and 9 years old. All but three of the children used a Nucleus 22 implant with the SPEAK coding strategy at the time of testing. Two of the children used a Clarion device and one child used a Nucleus 24 implant at the time of testing. The duration of implant use for all children was between 4 and 7.5 years. All of the children in this study produced a repetition response to at least 15 of the 20 target nonwords. The children’s responses were recorded on digital audiotape and then played back to 240 normal-hearing adult listeners for accuracy judgments. Normal-hearing listeners rated the accuracy of the children’s imitation responses against the original target models using a 7-point scale. The perceptual ratings of the children’s nonwords were strongly correlated with scores on separate independent measures of spoken word recognition, immediate memory span, and verbal rehearsal processes used in phonological working memory, as well as speech production skills. Children who had become deaf at slightly older ages and children who had been deaf for shorter periods of time prior to implantation received higher perceptual ratings. Children whose early linguistic experience and educational environments emphasized oral communication methods also received higher ratings than children enrolled in total communication programs. The findings from this study suggest that individual differences in performance on the nonword repetition task are strongly related to variability observed in the component processes involved in nonword repetition including speech perception, encoding and verbal rehearsal in phonological working memory, and speech production. In addition, a shorter period of deafness prior to implantation and an educational environment emphasizing oral communication may be beneficial to deaf children’s ability to develop the robust phonological processing skills that are necessary to accurately repeat novel, nonword stimuli. These skills appear to be related to more complex cognitive processes involved in word learning, vocabulary development, and speech production.