Effect of several acoustic cues on perceiving Mandarin retroflex affricates and fricatives in continuous speech

Relatively little attention has been paid to the perception of the three-way contrast between unaspirated affricates, aspirated affricates and fricatives in Mandarin Chinese. This study reports two experiments that explore the acoustic cues relevant to the contrast between the Mandarin retroflex series /tʂ/, /tʂ(h)/ and /ʂ/ in continuous speech. Twenty participants performed two three-alternative forced-choice tasks, in which acoustic cues including closure, frication duration (FD), aspiration, and vocalic contexts (VCs) were systematically manipulated and presented in a carrier phrase. A subsequent classification tree analysis shows that FD distinguishes /tʂ/ from /tʂ(h)/ and /ʂ/, and that closure cues the affricate manner. Interactions between VC and individual cues are also found. The FD threshold for separating /ʂ/ and /tʂ/ is susceptible to the influence of the following vocalic segments, shifting to lower values if frication is followed by the low vowel /a/. On the other hand, while aspiration cues /tʂ(h)/ before /a/ and //, this acoustic cue is obscured by gesture continuation when /tʂ(h)/ precedes its homorganic approximant /ɻ/ in natural speech, which might cause potential confusion between /tʂ(h)/ and /ʂ/.