Compensatory Use of Acoustic Speech Cues And Language Structure by Hearing-Impaired Listeners

Abstract

One of the goals of speech perception research is to determine the ways in which acoustic information is structured by the auditory periphery and the ways in which the central processor uses this information and codes it into meaningful linguistic units. When this information is altered or reduced by a change in the auditory periphery, for example through an acquired, noise-induced hearing loss, the central processor must then compensate for this loss either by restructuring the information or by using different acoustic cues or both. The purpose of the experiments described in this chapter is to find evidence of acoustic cues that can enable listeners with noise-induced hearing losses to compensate for missing cues, or evidence of a restructuring of the linguistic system to aid in speech perception. To this end listeners with normal hearing and hearing-impaired listeners were subjected to low-pass filtered speech so that a comparison could be made between the two groups and to test the relevance of simulating a hearing loss by means of lowpass filtered speech stimuli. Since a noise-induced hearing loss often entails high-frequency loss, low-frequency cues such as fundamental frequency (Fo) might provide material that could help the central processor in its recoding task. Fundamental frequency is particularly interesting as it provides normal listeners with important cues concerning syllable stress, the most important syllable, and sentence focus.