Three members of the Michigan Phonetics Laboratory, Andries Coetzee, Pam Beddor and Will Styler, are co-authors on a paper that recently appeared in the Journal of Phonetics. In this study, they document an interesting inter-generational difference in how historically voiced plosives are produced and perceived by Afrikaans speakers. They show that, while both older and younger speakers have large and robust differences in the fundamental frequency of vowels after historically voiced /b d/ and voiceless /p t/ plosives (fundamental frequency after /b d/ is lower by about 50 Hz than after /p t/), the historical voicing contrast between the plosive categories is collapsing (older speakers produce around 55% of /b d/ with voicing, but youngers speakers only about 15%). It therefore appears that the historical plosive voicing contrast of Afrikaans is being replaced by a tonal contrast. In addition to documenting how voiced and voiceless plosives are produced in Afrikaans, Coetzee and colleagues also investigate the perception of these plosives. They find that both older and younger listeners use fundamental frequency and plosive voicing as a cue to differentiate between the plosive categories, but that older listeners rely on voicing more than younger listeners. The perception patterns (older speakers rely on voicing more) therefore parallel the production patterns (older speakers produce more historically voiced plosives as voiced). The results are interpreted in the light of literature on sound change and differential cue weighting.

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