Shinji Maeda, Kiyoshi Honda
From EMG to formant patterns of vowels:
the implication of vowel systems spaces
Abstract:With a few exceptions [e.g., Kakita et al., 1985], EMG data are interpreted with reference to the intended output, such as the phonetic description of utterances spoken by speakers. For a more rigorous interpretation, the data should also be analyzed in terms of the displacement of the articulators and the acoustic patterns. In this paper, we describe our attempts to calculate the formant patterns from recorded EMG activities via an articulatory model [Maeda, 1990]. The value of the model parameters, such as the tongue-body position, tongue-body shape, is derived from the EMG activities of the specific pairs of antagonistic tongue muscles. The model-calculated F1-F2 patterns for 11 American English vowels correspond rather well with those measured from the acoustic signals. What strikes us is the simplicity of the mappings from the muscle activities, to vocal-tract configurations, and to the formant patterns. We speculate that the brain optimally exploits the morphology of the vocal tract and the kinematic functions of the tongue muscles so that the mappings from the muscle activities (production) to the acoustic patterns (perception) are simple and robust.