A PSYCHOACOUSTIC BASIS FOR DISSIMILATION: EVIDENCE FROM TANGKHUL NAGA

The dissimilation of sequential aspirated obstruents is investigated in Tangkhul Naga. Acoustic, aerody-namic, and perceptual data were gathered to under-stand the alternation between aspirated and unaspi-rated prefixes in the verbal morphology of the lan-guage. Production data confirm that prefix onsets are aspirated only when the onset of the following syllable is sonorous. Two prefixes may occur in se-quence. The traditional account predicts that the first of these will be unaspirated because it precedes an obstruent, not a sonorant. This is confirmed in the production data. However, perceptual data suggest that speakers of the language tend to hear an aspi-rated consonant in this position. This strengthens the claim that processing of repeated items is diffi-cult and perhaps dispreferred—a psychoacoustic ex-planation for phenomena such as Grassmann’s Law. This dissimilation pattern is still only perceptual in Tangkhul, but variation in production suggests dis-similation may be emerging at the production level also.