Nasalance in utterances of hearing-impaired speakers.

Instrumental comparisons of sound from the nose and mouth expressed in percent nasalance, articulation errors, and speech rate are used in this study to contrast utterances of 50 speakers with severe hearing impairment and 64 with normal hearing. Results of the study revealed that 54% of the hearing-impaired subjects had nasalance ratio scores greater than two standard deviations above the mean of the group with normal auditory acuity. No general relationship was found between the number or type of articulation errors and the nasalance scores. Rate of speaking was significantly related to the nasalance scores of the normal group but not those of the hearing-impaired group. Tonagrams displaying the variations in nasalance revealed small, 1 to 50% spike-shaped fluctuations in the displays of the utterances from both groups. Additional prolonged bursts of nasalance in excess of a 30% change in the ratio between the nasal and oral signal were common in the displays from the hearing-impaired group did not in those of the group with normal acuity. Possible sources and perceptual effects of these phenomena are discussed.