Effects of place of articulation and aspiration on voice onset time in Mandarin esophageal speech

The ability of Mandarin esophageal speakers to distinguish between aspirated and unaspirated stops, and to distinguish between different places of articulation of stops were examined. Aspirated and unaspirated voiceless stops produced by normal laryngeal (NL) and standard esophageal (SE) speakers were studied. VOT values of the five different stops (/p(h), t(h), k(h), p, t/) of Mandarin followed by the vowel /a/ produced by NL and SE speakers were compared. Results from the perceptual experiment indicated that, while voiceless unaspirated stops produced by SE speakers were not signaled with a high level of accuracy, voiceless aspirated stops were perceived correctly by the listeners. Acoustic analysis showed that SE speakers consistently produced shorter VOT than NL speakers. Velar stops were associated with significantly longer VOT values than bilabial and alveolar stops in NL speakers. It was also found that, with the use of the PE segment, SE speakers were still able to use VOT to distinguish between aspirated and unaspirated stops, but they were unable to distinguish between bilabial, alveolar, and velar places of articulation.