Lexical tone and vowel duration in San Sebastián del Monte Mixtec

Vowel duration has been shown to vary as a function of lexical tone (Gandour, 1977; Gordon, 2001; Yu, 2010). Here we explore the relationship between tone and duration in a dialect of Mixtec. San Sebastián del Monte Mixtec (SSM) has three tones which link to individual moras: H(igh) M(id) L(ow). These can be combined in a long (bimoraic) vowel, in some cases creating contour tones: HH MM LL HL ML LM (Cortes et al., forthcoming). Audio recordings of 14 native speakers (9F, 5M) were collected, producing 264 utterances with target words in phrase-medial position. The corpus includes all tones, as well as all vowels /i,e,a,o,u/ across four possible word shapes (with several lexical gaps). With mixed effects modeling, we find that duration varies as a function of tone with vowel and onset consonant controlled for (1) L tones are shorter than M and H tones in mono-moriacsyllables, and (2) tones in bimoraic (long vowel) monosyllabic words vary in duration as well: \MM,HH,LH\ \gt; \ML,LM,LL\. First vowels are longer, consistent with stress on the initial syllable. We further discuss the relation between duration, mean F0, and F0 range, and the influence of vowel features and preceding consonant on duration.