A perceptual experiment on Thai consonant types and tones

Abstract

Tonogenesis in Thai arose historically from neutralization of voicing contrast prevocalic consonants: new higher tonal variants after what had been voiceless consonants and new lower variants after the earlier voiced consonants. Today, Thai has again acquired a series of voiced stops and the same allophonic variation in F0 may be observed on the tones following voiced and voiceless stops. How important are these F0 cues to Thai listeners? Can one stage of the tonal multiplication process that shaped Thai tonal systems be demonstrated in the lab? A perceptual experiment was conducted. Six pairs of Thai words with voiced and voiceless initial stops were recorded, spliced at six different points of time, and put into contexts. These tokens were played to 11 native-Thai subjects for judgment as voiced or voiceless. The result showed that listeners tended to identify those syllables with gated-out bursts and closures as voiceless. However, there was a significant success at differentiating voiced and voiceless stops at gates past these points. It remains to be determined whether the cues that facilitate this are F0, vowel amplitude, or voice quality. If F0 plays a role, then this result mirrors the rise of distinctive tones in the Thai history.