LONG-TERM-MEMORY IN SPEECH-PERCEPTION - SOME NEW FINDINGS ON TALKER VARIABILITY, SPEAKING RATE AND PERCEPTUAL-LEARNING

This paper summarizes results from recent studies on the role of long- term memory in speech perception and spoken word recognition. Experime nts on talker variability, speaking Tate and perceptual learning provi de strong evidence for implicit memory for very fine perceptual detail s of speech. Listeners apparently encode specific attributes of the ta lker's voice and speaking rate into long-term memory. Acoustic-phoneti c variability does not appear to be ''lost'' as a result of phonetic a nalysis. The process of perceptual normalization in speech perception may therefore entail encoding of specific instances or ''episodes'' of the stimulus input and the operations used in perceptual analysis. Th ese perceptual operations may reside in a ''procedural memory'' for a specific talker's voice. Taken together, the present set of findings a re consistent with non-analytic accounts of perception, memory and cog nition which emphasize the contribution of episodic or exemplar-based encoding in long-term memory. The results from these studies also rais e questions about the traditional dissociation in phonetics between th e linguistic and indexical properties of speech. Listeners apparently retain non-linguistic information in long-term memory about the speake r's gender, dialect, speaking rate and emotional state, attributes of speech signals that are not traditionally considered part of phonetic or lexical representations of words. These properties influence the in itial perceptual encoding and retention of spoken words and therefore should play an important role in theoretical accounts of how the nervo us system maps speech signals onto linguistic representations in the m ental lexicon.