Simultaneous tracking of coevolving distributional regularities in speech.

Speech processing depends upon mapping variable acoustic speech input in a manner that reflects the long-term regularities of the native language. Yet, these mappings are flexible such that introduction of short-term distributional regularities in speech input, like those arising from foreign accents or talker idiosyncrasies, leads to rapid adjustments in the effectiveness of acoustic dimensions in signaling phonetic categories. The present experiments investigate whether the system is able to track simultaneous short-term distributional statistics present in speech input or if, instead, the global regularity jointly defined by these distributions dominates. Three experiments establish that adult listeners are able to track distinct simultaneously evolving regularities across time, given information to support the "binning" of acoustic instances. Both voice quality and visual information to indicate talker supported tracking of coevolving distributional regularities, even when the regularities are opposing and even when the acoustic speech tokens contributing to the distinct distributions are identical. This indicates that reweighting of perceptual dimensions in response to short-term regularities in speech input is not simply an accumulation of acoustic instances. Rather, the system is able to track multiple context-sensitive regularities simultaneously, with rapid context-dependent adaptive adjustments in how acoustic speech input maps to phonetic categories. (PsycINFO Database Record (c) 2018 APA, all rights reserved).