Speaker specific processing and local context information: The case of speaking rate
To deal with variation in the speech signal, listeners rely on local context, such as speaking rate in a carrier sentence directly preceding a target, as well as more global properties of the speech signal, such as speaker specific pronunciation variants. The present study addressed whether, despite its variability even within one speaker, habitual speaking rate can be tracked as a speaker specific property and how such speaker specific tracking of habitual rate would interact with effects of local rate normalization. In two experiments, listeners were exposed to a 2 min dialogue between a fast and a slow speaker. At test, listeners categorized minimal word pair continua differing in the German /a/ /a: duration contrast spoken by the same two speakers. The results showed that listeners responded with /a: more often for the fast speaker but only when words were presented in isolation and not when presented with additional local rate information. That is, despite the general assumption that duration cues and speaking rate are too variable to be used in a speaker specific fashion, tracking habitual speaking rate may help speech perception. The results are discussed in relation to a belief updating model of perceptual adaptation and exemplar models.