The Effects of Contextual Strength on Phonetic Identification in Younger and Older Listeners

Abstract

It has often been reported that older listeners have difficulty discriminating between phonetically similar items, but may rely on contextual cues as a compensatory mechanism. The present study examined the effects of different degrees of semantic bias on speech perception in groups of younger and older listeners. Stimuli from two /g/-/k/ voice onset time (VOT) continua were presented at the end of biasing and neutral sentences. Results indicated that context strongly influenced phonetic identification in older listeners; this was true for younger listeners only in the case of less-than-ideal stimuli. Findings are discussed in relation to theories concerning age-related changes in speech processing.

This research was supported by a grant from the Canadian Institutes of Health Research to Shari R. Baum. The authors thank Jason McDevitt for help recording stimuli and Erin Vensel for her help in data collection.

Notes

¹The phonetic category boundary is defined as that point along the continuum at which listeners produce 50% identification responses consistent with each end point. As noted, this boundary may shift from that found under neutral conditions.

²Although there may be subtle variations in cognitive performance among both participant groups despite normal MMSE scores, we simply wanted to rule out global impairment.

Note. The values in parentheses are standard errors.

Note. The values in parentheses are standard errors.

^3,4The data were also arcsine-transformed; results of the subsequent ANOVA were identical.