Abstract:

Acoustic and articulatory recordings indicate that speakers utilize trade-offs between different articulatory parameters to maintain acoustic stability during American English /r/ productions. Electromagnetic midsagittal articulometer data from seven subjects producing /r/ in five phonetic contexts were analyzed. Articulator configurations for /r/ in different contexts showed systematic trade-offs between constriction length, constriction area, and front cavity volume. The hypothesized effects of these three parameters on F3, derived from acoustic theory, were verified using a 51-tube model of the vocal tract derived from structural MRI scans of a speaker producing /r/. All seven subjects utilized a trade-off between front cavity volume and the length of the constriction formed by the tongue. Further analysis of acoustic and articulatory variabilities indicates that the net effect of these articulatory covariances is a considerable reduction in acoustic variability, thus allowing large contextual variations in vocal tract shape; these contextual variations in turn appear to reduce the total amount of articulatory movement required. These findings contrast with the view that speaking involves a target set of vocal tract constrictions for each phoneme and provide strong evidence for acoustic theories of speech production. [Work supported by NIDCD, NSF, and the Sloan Foundation.]