Effects of vowel coproduction on the timecourse of tone recognition

Vowel contrasts tend to be perceived independently of pitch modulation, but it is not known whether pitch can be perceived independently of vowel quality. This issue was investigated in the context of a lexical tone language, Mandarin Chinese, using a printed word version of the visual world paradigm. Eye movements to four printed words were tracked while listeners heard target words that differed from competitors only in tone (test condition) or also in onset consonant and vowel (control condition). Results showed that the timecourse of tone recognition is influenced by vowel quality for high, low, and rising tones. For these tones, the time for the eyes to converge on the target word in the test condition (relative to control) depended on the vowel with which the tone was coarticulated with /a/ and /i/ supporting faster recognition of high, low, and rising tones than /u/. These patterns are consistent with the hypothesis that tone-conditioned variation in the articulation of /a/ and /i/ facilitates rapid recognition of tones. The one exception to this general pattern—no effect of vowel quality on falling tone perception—may be due to fortuitous amplification of the harmonics relevant for pitch perception in this context.