Vocal/verbal response times of normal-hearing and hearing-impaired children

A series of experiments are reported that contrast vocal/verbal reaction-time measures from 16 normal-hearing and 25 hearing-impaired children 7 to 14 years old. Sixteen of the hearing-impaired children were enrolled in a residential school, 9 in a day school. Vocal reaction time of the children in response to visually presented stimuli was measured in four tasks: phonating "uh", saying the word "one", counting to digits, and naming digits. No significant differences were found between the response latencies of the two hearing-impaired groups on any task. Nor were differences found between the normal and hearing-impaired groups when the task was simply phonating "uh". Differences between these groups began to emerge when the word "one" was spoken. These differences increased systematically with the phonetic complexity of the task. Hearing level, latency in the counting responses, and magnitude of a ratio between phonating and digit counting latencies were identified as major predictors of speech intelligibility. The results suggest that central phonetic processing functions may be related to the quality of speech production by hearing-impaired talkers.