Variability in individual constriction contributions to third formant values in American English /ɹ/

Although substantial variability is observed in the articulatory implementation of the constriction gestures involved in /ɹ/ production, studies of articulatory-acoustic relations in /ɹ/ have largely ignored the potential for subtle variation in the implementation of these gestures to affect salient acoustic dimensions. This study examines how variation in the articulation of American English /ɹ/ influences the relative sensitivity of the third formant to variation in palatal, pharyngeal, and labial constriction degree. Simultaneously recorded articulatory and acoustic data from six speakers in the USC-TIMIT corpus was analyzed to determine how variation in the implementation of each constriction across tokens of /ɹ/ relates to variation in third formant values. Results show that third formant values are differentially affected by constriction degree for the different constrictions used to produce /ɹ/. Additionally, interspeaker variation is observed in the relative effect of different constriction gestures on third formant values, most notably in a division between speakers exhibiting relatively equal effects of palatal and pharyngeal constriction degree on F3 and speakers exhibiting a stronger palatal effect. This division among speakers mirrors interspeaker differences in mean constriction length and location, suggesting that individual differences in /ɹ/ production lead to variation in articulatory-acoustic relations.