Influence of fundamental frequency on stop-consonant voicing perception: A case of learned covariation or auditory enhancement?

Abstract

Listeners labeling members of an acoustic series modeling VOT (e.g., /ba/-/pa/) are more likely to identify tokens with higher f0 as voiceless than they are for otherwise-identical tokens with lower f0s. This pattern of results may arise because a high f0 enhances perception of voicelessness, in line with auditory enhancement accounts of speech perception. Alternatively, because f0 and VOT covary in English production, it is possible that listeners respond in this manner due to experience with VOT/f0 covariation in the speech signal. The present investigation was designed to tease apart the relative contributions of these two potential mechanisms. Japanese quail (Coturnix coturnix japonica) were trained to ‘‘label’’ stimuli drawn from VOT series by pecking a key. During training, each quail experienced one of three styles of VOT/f0 covariation. For one group of quail, VOT and f0 covaried naturally with voiceless series members having higher f0s than voiced members. Another group of quail heard the inverse, ‘‘unnatural’’ covariation. A final group experienced stimuli for which there was no covariation between VOT and f0. Results indicate that experience with VOT/f0 covariation is the predominant force in shaping perception. Thus, general learning mechanisms may account for this symmetry between perception and production.