Effects of native language on perception of voice quality.

Little is known about how listeners judge phonemic versus allophonic (or freely varying) versus post-lexical variations in voice quality, or about which acoustic attributes serve as perceptual cues in specific contexts. To address this issue, native speakers of Gujarati, Thai, and English discriminated among pairs of voices that differed only in the relative amplitudes of the first versus second harmonics (H1-H2). Results indicate that speakers of Gujarati (which contrasts H1-H2 phonemically) were more sensitive to changes than are speakers of Thai or English. Further, sensitivity was not affected by the overall source spectral slope for Gujarati speakers, unlike Thai and English speakers, who were most sensitive when the spectrum fell away steeply. In combination with previous findings from Mandarin speakers, these results suggest a continuum of sensitivity to H1-H2. In Gujarati, the independence of sensitivity and spectral context is consistent with use of H1-H2 as a cue to the language's phonemic phonation contrast. Speakers of Mandarin, in which creaky phonation occurs in conjunction with the low dipping Tone 3, apparently also learn to hear these contrasts, but sensitivity is conditioned by spectral context. Finally, for Thai and English speakers, who vary phonation only post-lexically, sensitivity is both lower and contextually-determined, reflecting the smaller role of H1-H2 in these languages.