The articulatory properties of apical vowels in Hefei Mandarin

Apical vowels are widely observed across Chinese dialects, such as the rime of [sɹ̩⁵⁵] ‘think’ in Mandarin Chinese, which is a syllabic approximant homorganic to its preceding sibilant. The apical vowels in Hefei Mandarin differ from those in Mandarin Chinese and most other languages in three aspects: (i) there are three phonetic apical vowels [ɹ̩], [ɹ̩ʷ], and [ɻ̩] while others usually have one or two, (ii) the alveolar apical [ɹ̩] appears after both homorganic and non-homorganic consonants, e.g. [sɹ̩] vs. [pɹ̩], and (iii) there is a phonological contrast between an unrounded apical [ɹ̩] and a rounded apical [ɹ̩ʷ], e.g. [sɹ̩] vs. [sɹ̩ʷ]. The articulatory properties of the three apical vowels were examined in this study using ultrasound techniques and the results revealed that: (i) the commonalities of tongue gestures for the apical vowels include a retracted tongue root, a lowered tongue dorsum or blade, or both, together with a coronal constriction implemented with the blade and/or the tip; (ii) lip gestures are involved in distinguishing the three apical segments; (iii) the three segments each have its distinct articulatory gestures within a speaker that cannot be simply attributed to the influence from their preceding consonants, with [ɹ̩] and [ɹ̩ʷ] involving a grooving in the front part of the tongue and [ɻ̩] involving a retraction of tongue body in the back region of the vocal tract; (iv) the articulatory gesture of [ɹ̩] after a homorganic consonant, e.g. in [sɹ̩], is similar to that after a non-homorganic consonant, e.g. in [pɹ̩], suggesting an independent articulatory target for this segment.