Perception of cues to coda stop voicing in Australian English

A number of cues may signal the phonemic contrast between voiced and voiceless coda stops (e.g. /t/ and /d/) including preceding vowel duration and coda closure duration, as well as the ratio between these two components of the rhyme (Lisker, 1957; Port & Dalby, 1982, Raphael, 1972). Previous research suggests that Australian English (AusE) speakers additionally utilise glottalisation to cue coda stop voicelessness (Penney et al. 2018). This appears to be a recent change, with older speakers producing less glottalisation than younger speakers. However, it is not known whether listeners utilise this cue in perception, or how this interacts with other cues to voicing. We present the results of a set of perceptual experiments designed to examine how AusE listeners perceive cues to coda stop voicing and whether this differs across age groups.

Seventy-seven listeners from two age groups (older: 31; younger: 46) took part in a forced choice word identification task. We presented participants with audio stimuli in which vowel and coda closure durations were manipulated, both separately and in combination. We also manipulated the presence of glottalisation. Results suggest that AusE listeners make use of preceding vowel duration to cue coda stop voicing, with longer vowels cueing voiced coda stops, and shorter vowels cueing voiceless coda stops. Listeners do not appear to utilise coda closure duration to the same extent as vowel duration, unless it is varied as a proportion of the rhyme in combination with vowel duration. This suggests that vowel duration may be the more important element of the rhyme in cueing coda stop voicing, consistent with previous findings (Luce & Charles–Luce, 1985). In addition, the results show that glottalisation facilitates increased perception of coda stop voicelessness. Despite differences in production, the results show that older and younger listeners use these cues similarly in perception.

References

Lisker, L. (1957). Closure Duration and the Intervocalic Voiced-Voiceless Distinction in English. Language, 33, 42–49.

Luce, P. A., & Charles–Luce, J. (1985). Contextual effects on vowel duration, closure duration, and the consonant/vowel ratio in speech production. Journal of the Acoustical Society of America, 78, 1949–1957.

Port, R. F., & Dalby, J. (1982). Consonant/vowel ratio as a cue for voicing in English. Perception and Psychophysics, 32, 141-152.

Penney, J., Cox, F., Miles, K., & Palethorpe, S. (2018). Glottalisation as a cue to coda consonant voicing in Australian English. Journal of Phonetics, 66, 161–184.

Raphael, L. J. (1972). Preceding vowel duration as a cue to the perception of the voicing characteristic of word-final consonants in American English. Journal of the Acoustical Society of America, 51, 1296–1303.