On some issues in the pursuit of acoustic invariance in speech: a reply to Lisker.

This paper presents an alternative view of acoustic invariance in speech to that discussed by Lisker [J. Acoust. Soc. Am. 77, 1199-1202 (1985)]. Three points are considered--the minimal unit for acoustic invariance, the level of linguistic representation over which this unit operates, and the role that acoustic invariance plays in speech and language. Our position emphasizes the role of phonetic features in a theory of acoustic invariance, and we propose a series of working hypotheses to guide research in this area.