Sibilant Fricative Merging in Taiwan Mandarin: An Investigation of Tongue Postures using Ultrasound Imaging.
Chenhao Chiu, Po-Chun Wei, Masaki Noguchi and 1 others
PMID 31888408WHAT IT FOUND
Seven Taiwan Mandarin speakers showed varied tongue postures for dental and retroflex sounds.
Two merged them articulatorily and acoustically. Three kept distinct sounds despite some tongue overlap, likely using lip rounding. This highlights individual variation in how these speech sounds are physically produced.
Key findings
01Two participants showed merged tongue postures and similar acoustic frequencies for dental [s] and retroflex [ʂ] across all vowel contexts.
02Three participants merged tongue postures only in specific vowel contexts, yet maintained distinct acoustic frequencies, suggesting other gestures like lip rounding compensated for the lack of tongue contrast.
03Native listeners confused dental [s] and retroflex [ʂ] more often when produced by the speakers who had merged tongue postures and acoustic frequencies.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Small sample size of seven participants limits generalizability. Only mid-sagittal tongue postures were examined, ignoring other potential compensatory gestures like lip rounding or lateral tongue movements. Data came from lab speech, which may differ from natural connected speech. Proficiency in Taiwan Southern Min, a language lacking retroflex sounds, was not controlled for, though the authors noted it did not clearly predict merging patterns.
Declared interests
None reported.
The easy way to misread this
Do not assume that merged tongue postures on ultrasound always result in merged speech sounds. Some speakers maintained distinct acoustic outputs despite overlapping tongue positions, likely by using other articulators not captured in this study.