Over the past several years, I have conducted a series of studies on variation in the articulation of the Northern Cities Vowel Shift (NCVS). While the NCVS stands as one of the most widely studied examples of a sound change in progress, very few studies consider how this sound change, or any other sound change, is realized in terms of its articulation. In an ultrasound study of speakers from Metro Detroit, I find variability with respect to how fronted /ɔ/ is articulated, suggesting that speakers can use differing articulatory configurations to achieve the same sound change.
Havenhill, Jonathan. 2015a. An ultrasound analysis of the low back vowels in the Northern Cities Vowel Shift. Proceedings of the 18th International Congress of Phonetic Sciences, ed. by The Scottish Consortium for ICPhS 2015. Glasgow, UK: University of Glasgow. [PDF]
Havenhill, Jonathan. 2015b. Maintenance of the cot-caught contrast among Detroit speakers: A multimodal articulatory analysis. University of Pennsylvania working papers in linguistics, Selected papers from NWAV 43, 21: 2. Philadelphia, PA: University of Pennsylvania. [PDF]
In joint work with Elizabeth Zsiga, One Tlale Boyer, and Stacy Petersen (Georgetown University), I have pursued an investigation into the labiocoronal fricatives of Setswana and Sebirwa, which are described in the literature as exhibiting frication at both a lingual and a labial constriction. We conducted a study of these sounds with a combination of ultrasound, video, acoustic, and aerodynamic analysis. We argue that the sound is not in fact doubly articulated, but instead exhibits a distinct type of secondary labialization whereby the lips are compressed rather than rounded. We have presented various aspects of this work at Ultrafest VIII and the 2017 Annual Meeting on Phonology.