An exploratory study into perception of acoustic speech cues by hearing-impaired adults

The aims of the present study were to assess discrimination and identification based on two classes of acoustic cue by adults with acquired sensorineural hearing impairment. Eight hearing-impaired and eight normally hearing adults were asked to identify and discriminate two different sets of speech stimuli. A plosive voicing continuum (coat/goat) varied in voice onset time. The plosive place of articulation continuum (date/gate) varied in burst spectra and second formant transition. Subjects were tested in the unaided condition with the exception of one hearing-impaired subject for whom speech was completely inaudible without a hearing aid. There was no significant between-group difference in discrimination or identification of the voicing contrast. There was no significant between-group difference in identification of stimuli varying by place of articulation. However, three of the eight hearing-impaired subjects were very poor at identification. The hearing-impaired subjects also showed significantly impaired place of articulation discrimination. Both measures were significantly correlated with threshold at 2000 Hz. The results support the view that hearing impairment can have different effects on perception of different acoustic contrasts and on different psychophysical tasks.