Revisiting the nature and the context of T4 alternations: insights from disyllabic, trisyllabic and quadrisyllabic word/digit productions in Taiwan Mandarin.

The tone values of a Tone 4 (T4) syllable are conventionally assumed to change from '51' to '53' when the syllable is followed by another T4 syllable in Mandarin Chinese. Literature focusing on T4 alternation is still inconclusive regarding the contexts for the alternations and whether the phenomenon should be better categorized as tone sandhi (i.e., represented as an abstract phonological rule in mental grammar) or tonal coarticulation (i.e., a natural articulation phenomenon at the phonetic level). The current study probes into these issues by focusing on disyllabic pseudowords, right-branching trisyllabic words as well as unstructured trisyllabic and quadrisyllabic digits. Productions from a total of 148 participants were collected and fundamental frequency (f0) contours, vowel lengths and f0 slopes were included in the analysis. The results from the experiments supported the tonal coarticulation view and showed that the trigger for the alternations was the high-onset tones following T4. Implications to the phonological analysis on tonal alternations in Mandarin Chinese are discussed.