A real-time magnetic resonance imaging study of cross-speaker variability in the production of /ɹ/

There is a longstanding interest in understanding the production mechanisms of the American English (AE) rhotic, /ɹ/ especially given both the wide intraspeaker variability and interspeaker heterogeneity in its articulation, and the resultant acoustics. A diversity of tongue shapes, from those creating a more anterior tongue-tip (“retroflex”) constriction to those with a more posterior bunched tongue dorsum constriction, has been observed with notable intraspeaker variation as a function of context; more specifically, a tendency for retroflexion preceding low and/or back vowels. The present study aims to analyze AE /ɹ/ production using real-time MRI videos (83 frames/s) where the target sound was produced in several contexts by 32 American English speakers (16 F/16 M). Initial findings in symmetric VCV production reveal that some of these speakers exclusively use a “retroflex” strategy, some a “bunched” strategy, and others both strategies, consistent with the previously observed tendencies. This observed variability, and the fact that multiple types of static and dynamic imaging data are available from the same speakers, makes this dataset ideal for further probing /ɹ/ production strategies in conjunction with speaker-specific characteristics of vocal tract structure, such as palate shape, and function, such as inter-articulator coordination. [Work supported by NIH and NSF.]