Maintaining information about speech input during accent adaptation.

Speech understanding can be thought of as inferring progressively more abstract representations from a rapidly unfolding signal. One common view of this process holds that lower-level information is discarded as soon as higher-level units have been inferred. However, there is evidence that subcategorical information about speech percepts is not immediately discarded, but is maintained past word boundaries and integrated with subsequent input. Previous evidence for such subcategorical information maintenance has come from paradigms that lack many of the demands typical to everyday language use. We ask whether information maintenance is also possible under more typical constraints, and in particular whether it can facilitate accent adaptation. In a web-based paradigm, participants listened to isolated foreign-accented words in one of three conditions: subtitles were displayed concurrently with the speech, after speech offset, or not displayed at all. The delays between speech offset and subtitle presentation were manipulated. In a subsequent test phase, participants then transcribed novel words in the same accent without the aid of subtitles. We find that subtitles facilitate accent adaptation, even when displayed with a 6 second delay. Listeners thus maintained subcategorical information for sufficiently long to allow it to benefit adaptation. We close by discussing what type of information listeners maintain-subcategorical phonetic information, or just uncertainty about speech categories.

Rapid adaptation to foreign-accented speech and its transfer to an unfamiliar talker.

How fast can listeners adapt to unfamiliar foreign accents? Clarke and Garrett [J. Acoust. Soc. Am. 116, 3647-3658 (2004)] (CG04) reported that native-English listeners adapted to foreign-accented English within a minute, demonstrating improved processing of spoken words. In two web-based experiments that closely follow the design of CG04, the effects of rapid accent adaptation are examined and its generalization is explored across talkers. Experiment 1 replicated the core finding of CG04 that initial perceptual difficulty with foreign-accented speech can be attenuated rapidly by a brief period of exposure to an accented talker. Importantly, listeners showed both faster (replicating CG04) and more accurate (extending CG04) comprehension of this talker. Experiment 2 revealed evidence that such adaptation transferred to a different talker of a same accent. These results highlight the rapidity of short-term accent adaptation and raise new questions about the underlying mechanism. It is suggested that the web-based paradigm provides a useful tool for investigations in speech adaptation.