The role of creaky voice in Cantonese tonal perception.

There are few studies on the role of phonation cues in the perception of lexical tones in tonal languages where pitch is the primary dimension of contrast. This study shows that listeners are sensitive to creaky phonation in native tonal perception in Cantonese, a language in which the low falling tone, Tone 4, has anecdotally been reported to be sometimes creaky. First, in a multi-speaker corpus of lab speech, it is documented that creak occurs systematically more often on Tone 4 than other tones. Second, for stimuli drawn from this corpus, listeners identified Tone 4 with 20% higher accuracy when it was realized with creak than when it was not. Third, in a two-alternative forced choice task of identifying stimuli as Tone 4 or Tone 6 (the low level tone) isolating creak from any concomitant pitch cues, listeners had a higher proportion of Tone 4 responses for creaky stimuli. Finally, listeners had more Tone 4 responses for creaky stimuli with longer durations of nonmodal phonation. These results underscore that differences in voice quality contribute to human perception of tone alongside f0. Automatic tonal recognition and clinical applications for tone would benefit from attention to voice quality beyond f0 and pitch.