Abstract
Nonspeech stimuli influence phonetic categorization, but effects observed so far have been limited to precursors' influence on perception of following speech. However, both preceding and following speech affect phonetic categorization. This asymmetry raises questions about whether general auditory processes play a role in context-dependent speech perception. This study tested whether the asymmetry stems from methodological issues or genuine mechanistic limitations. To determine whether and how backward effects of nonspeech context on speech may occur, one experiment examined perception of CVC words with [ga]-[da] series onsets followed by one of two possible embedded tones and one of two possible final consonants. When the tone was separated from the target onset by 100 ms, contrastive effects of tone frequency similar to those of previous studies were observed; however, when the tone was moved closer to the target segment assimilative effects were observed. In another experiment, contrastive effects of a following tone were observed in both CVC words and CV nonwords, although the size of the effects depended on syllable structure. Results are discussed with respect to contrastive mechanisms not speech-specific but operating at a relatively high level, taking into account spectrotemporal patterns occurring over extended periods before and after target events.
Highlights
Human perception of speech sounds is heavily influenced by the acoustic properties of the contexts in which the sounds are heard
The present study demonstrates that later-occurring nonspeech acoustic events can influence categorization of preceding speech
Higher-frequency following tones caused ambiguous speech targets to be identified as the lower-F3 consonant alternativeg, and vice versa. This finding adds to the array of findings in which nonspeech acoustic context has been shown to parallel speech context in its perceptual influence on speech
Summary
The coarticulatory effects of neighboring sounds, allowing for accurate identification. Since the contrastive influence of context-providing stimuli seems to be contingent on their perceptual continuity with target eventse.g., McCollough, 1965; Walker and Irion, 1979͒, it may be essential that listeners group the nonspeech events into a single stream with targeted speech sounds This is especially critical when the context follows, rather than precedes, the target speech sound since the context can exert no effect if listeners make phonetic decisions before it is presented. Should perceptual grouping along these lines occur, observable context effects of the nonspeech tones on speech categorization would be assimilative rather than contrastive in direction and could override or obscure any effects of perceptual contrast that might occur In light of these methodological concerns, the present study attempts to strike a balance between providing for acoustic continuity such that nonspeech context is grouped into a context-providing stream with an earlier-occurring speech target while ensuring that the two are not perceived as information for a single event. Experiment 2 tested the limits of this experimental design, examining whether any observed patterns would hold up in the absence of the lexical task or the CVC stimulus structure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
