Rate of transition as a cue for place perception in normal and hearing‐impaired listeners

Abstract

Recent research exploring the role of rate of transition in the identification of place of articulation of stop consonants revealed that rate of transition influences place perception when formant frequencies are ambiguous between [da] and [ga] [Zakia and Kingston, J. Acoust. Soc. Am. Suppl. 1 85, S 135 (1989)]. In the experiments reported here, variations in F1, F2, and F3 transitions between values appropriate for [dr] and values appropriate for [gɛ] were combined with variations in rate of transition in 5‐ms steps between 20 and 60 ms. Stimuli were presented to two populations of young listeners, one with normal hearing and the other with mild hearing impairment of postlingual onset, in one‐and two‐interval forced choice identification of place of articulation tasks. It is predicted that normal‐hearing listeners will identify stimuli with longer transition durations as [gɛ] and stimuli with shorter transition durations as [dɛ] at “intermediate” formant patterns (i.e., those which specify neither [dɛ] nor [gɛ]). Performance of hearing‐impaired listeners on the same task is predicted to be poorer overall, as they suffer a decreased ability to identify place of articulation from transition information alone [Q. Summerfield et al., Speech Commun. 4, 213–229 (1985)]. Furthermore, if the poorer temporal resolution characteristic of hearing impairment leads to distortion of the distribution of spectral energy over time, it is predicted that rate of transition will not aid hearing‐impaired subjects in identifying place of articulation or bias their judgment when formant frequencies are ambiguous between [dɛ] and [gɛ]. [Work supported by the International Center for Hearing and Speech Research.]