ABSTRACT
Word-level prosody plays an important role in processes of consonant lenition. Typically, consonants in word-initial position are strengthened while those in word-medial position are lenited (Keating et al., 2003). In this paper we examine the relationship between wordprosodic position and obstruent lenition in a spontaneous speech corpus of Yoloxóchitl Mixtec, an endangered Mixtecan language spoken in Mexico. The language exhibits a surprising amount of lenition in the realization of otherwise voiceless unaspirated stops and voiceless fricatives in careful speech. In Experiment 1, we examine the relationships between word position, consonant duration, and passive voicing and find that word-medial pre-tonic position is the locus of both consonant lengthening and less passive voicing. Non-pre-tonic consonants are produced with more voicing and shorter duration. We also find that the functional status of the morpheme plays a role in voicing lenition. In Experiment 2, we examine manner lenition and find a similar pattern - word-medial pre-tonic stops are more often realized with complete closure relative to non-pre-tonic stops, which are more often realized with incomplete closure. In Experiment 3, we model these lenition patterns using a series of deep neural networks and find that, even with limited training data, we can achieve reasonably high accuracy in the automatic categorization of lenition patterns. The results of this research both complement recent work on the phonetics of lenition in the world's languages (Katz and Fricke, 2018; White et al., 2020) and provide computational tools for modeling and predicting patterns of extreme lenition.
ABSTRACT
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.
