title: Are articulatory settings mechanically advantageous for speech motor control?
abstract: We address the hypothesis that postures adopted during grammatical pauses in speech production are more "mechanically advantageous" than absolute rest positions for facilitating efficient postural motor control of vocal tract articulators. We quantify vocal tract posture corresponding to inter-speech pauses, absolute rest intervals as well as vowel and consonant intervals using automated analysis of video captured with real-time magnetic resonance imaging during production of read and spontaneous speech by 5 healthy speakers of American English. We then use locally-weighted linear regression to estimate the articulatory forward map from low-level articulator variables to high-level task/goal variables for these postures. We quantify the overall magnitude of the first derivative of the forward map as a measure of mechanical advantage. We find that postures assumed during grammatical pauses in speech as well as speech-ready postures are significantly more mechanically advantageous than postures assumed during absolute rest. Further, these postures represent empirical extremes of mechanical advantage, between which lie the postures assumed during various vowels and consonants. Relative mechanical advantage of different postures might be an important physical constraint influencing planning and control of speech production.
authors.affiliation: Signal Analysis and Interpretation Laboratory, Viterbi School of Engineering, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Vikram
authors.initials: V
authors.lastname: Ramanarayanan
authors.affiliation: Signal Analysis and Interpretation Laboratory, Viterbi School of Engineering, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Adam
authors.initials: A
authors.lastname: Lammert
authors.affiliation: Department of Linguistics, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Louis
authors.initials: L
authors.lastname: Goldstein
authors.affiliation: Signal Analysis and Interpretation Laboratory, Viterbi School of Engineering, University of Southern California, Los Angeles, California, United States of America; Department of Linguistics, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Shrikanth
authors.initials: S
authors.lastname: Narayanan
mesh_terms: D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007568:Jaw / Q000502:physiology; D008046:Lip / Q000502:physiology; D009048:Motor Skills; D011187:Posture; D013061:Speech Acoustics; D014059:Tongue / Q000502:physiology; D014827:Vocal Cords / Q000502:physiology