Quantifying labial, palatal, and pharyngeal contributions to third formant lowering in American English /ɹ/

Although the acoustic profile of /ɹ/ is largely stable across speakers and contexts in rhotic dialects of American English (e.g., Hagiwara, 1995), significant variability is observed in the articulatory implementation of the palatal, pharyngeal, and labial constriction gestures involved in its production (Delattre & Freeman, 1968; Alwan et al., 1999; Tiede et al., 2004). In order to quantify each gesture’s relative contribution to F3 lowering, we expand upon previous work on articulatory-acoustic relations in American English /ɹ/ by examining the acoustic effect of articulatory variation separately for each supralaryngeal constriction gesture. Real-time MRI data from four speakers in the USC-TIMIT corpus (Narayanan et al., 2014) were analyzed to determine the location, length, and aperture for each constriction gesture in 668 tokens of /ɹ/. Acoustic data were taken from simultaneous audio recordings of each speaker’s real-time MRI capture, with F1-F4 values extracted at the time of maximal constriction fo...