Standard Mandarin (SM) apical vowels have tongue postures similar to the fricative consonants that obligatorily precede them, but are thought to lack the consonants’ fricative noise. Lee-Kim  argues that in SM apical vowels, a slight reduction of constriction at the tongue blade or tip reduces fricative noise, essentially resulting in syllabic approximants. Using lingual ultrasound to examine articulation of apical vowels in SM, we argue that other articulatory adjustments may also limit frication in apical vowels, but that these strategies are implemented variably such that some speakers occasionally exhibit frication. This articulatory variety mostly maps to frictionless or approximant-like apical vowels in SM, but we find no reason to rule out fricativized apical vowels as possible phonetic segments in SM or other languages.
January 1, 2015
Faytak, Matthew and Susan Lin. 2015. Articulatory variability and fricative noise in apical vowels. Proceedings of the 18th International Congress of Phonetic Sciences.