Acoustic modeling of American English /r/

Abstract

Recent advances in physiological data collection methods have made it possible to test the accuracy of predictions against speaker-specific vocal tracts and acoustic patterns. Vocal tract dimensions for /r/ derived via magnetic-resonance imaging (MRI) for two speakers of American English [Alwan, Narayanan, and Haker, J. Acoust. Soc. Am. 101, 1078-1089 (1997)] were used to construct models of the acoustics of /r/. Because previous models have not sufficiently accounted for the very low F3 characteristic of /r/, the aim was to match formant frequencies predicted by the models to the full range of formant frequency values produced by the speakers in recordings of real words containing /r/. In one set of experiments, area functions derived from MRI data were used to argue that the Perturbation Theory of tube acoustics cannot adequately account for /r/, primarily because predicted locations did not match speakers' actual constriction locations. Different models of the acoustics of /r/ were tested using the Maeda computer simulation program [Maeda, Speech Commun. 1, 199-299 (1982)]; the supralingual vocal-tract dimensions reported in Alwan et al. were found to be adequate at predicting only the highest of attested F3 values. By using (1) a recently developed adaptation of the Maeda model that incorporates the sublingual space as a side branch from the front cavity, and by including (2) the sublingual space as an increment to the dimensions of the front cavity, the mid-to-low values of the speakers' F3 range were matched. Finally, a simple tube model with dimensions derived from MRI data was developed to account for cavity affiliations. This confirmed F3 as a front cavity resonance, and variations in F1, F2, and F4 as arising from mid- and back-cavity geometries. Possible trading relations for F3 lowering based on different acoustic mechanisms for extending the front cavity are also proposed.

A unified account of categorical effects in phonetic perception

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Vocal production mechanisms in a non-human primate: morphological data and a model

“…This is because the same or similar formant patterns can be obtained with a range of different vocal tract configurations (see for example discussion in Espy-Wilson et al, 2000). In this study, we only incorporated assumptions that were based on empirical evidence provided by our anatomical findings or on facts provided by earlier investigations.…”

The Early Phase of /ɹ/ Production Development in Adult Japanese Learners of English

“…Nonetheless, a common articulation is bunched-tongue /ɹ/, in which the tongue apex is not raised, but constrictions occur at the palate and in the lower pharynx. Irrespective of articulatory configuration, a defining acoustic property of /ɹ/ is a characteristic drop in F3 frequency (to < 2400 Hz) due to three simultaneous constrictions in the labial, palatal, and pharyngeal areas of the vocal tract (Espy-Wilson et al, 2000). In addition, F2 typically ranges between 1700 and 2100 Hz, with F1 between 250 and 550 Hz.…”