Disentangling the Effects of Position and Utterance-Level Declination on the Production of Complex Tones in Yoloxóchitl Mixtec

Phrase-final position is cross-linguistically the locus of both processes of phonetic reduction and processes of phonetic enhancement. In tone languages, phrasal position is a conditioning environment for processes of tone sandhi/allotony, though such patterns emerge from local processes of tonal enhancement or reduction. The current article examines the production of tone in Yoloxóchitl Mixtec, an endangered language of Mexico with nine lexical tones and fixed, stem-final stress, across phrasal and utterance positions via three experiments. In the first two experiments, the findings show that speakers lengthen syllables and expand the tonal F0 range in utterance-final position. The effect of this range expansion is high tone raising, low tone lowering, and falling contour lowering. Rising contour tones undergo substantial leveling when produced in a non-utterance-final context, similar to Taiwanese Mandarin. These findings suggest that postural changes in F0 range are controlled, intonational effects in tonal languages and not paralinguistic. In the third experiment, we examine utterance-level declination and raising within sentences consisting entirely of level tones. We show that utterance-level F0 changes are independent from local tonal hyperarticulation effects in phrase-final position. Together, the experiments largely support prosodically-conditioned phonetic undershoot as a control mechanism in tone production and demonstrate how tonal complexity may constrain universal tendencies in speech production.