Vowel Length Perception in Cantonese

This paper reports the acoustic experiment and perception test on a pair of Cantonese long and short vowels /a/ and /ɐ/ in the diphthong context. The acoustic data show that [aːi] and [ɐi] have similar targets of vowel nucleus and coda, parallel transition glide, and comparable total duration. They are different in their durational structure: [aːi] has a long steady phrase of vowel nucleus while its coda is short. In contrast, the vowel nucleus of [ɐi] is short but its coda lasts long. The situation of [aːu] and [ɐu] is also similar. In the perception test, the unidirectional gradual cutting method is adopted to change the duration ratio of vowel nucleus and coda. Progressive cutting [aːi]/[aːu] can make them sound like [ɐi]/[ɐu], while regressive cutting [ɐi]/[ɐu] can turn them into [aːi]/[aːu], which prove that these pairs of diphthongs are different in durational structure rather than vowel quality. Furthermore, borrowing the idea of the least square method, our re-analysis of the stimuli reveals that the length of vowel nucleus plays a more important role than the quality of transition glide and coda target in perception.