title: Three speech sounds, one motor action: evidence for speech-motor disparity from English flap production.
abstract: The assumption that units of speech production bear a one-to-one relationship to speech motor actions pervades otherwise widely varying theories of speech motor behavior. This speech production and simulation study demonstrates that commonly occurring flap sequences may violate this assumption. In the word "Saturday," a sequence of three sounds may be produced using a single, cyclic motor action. Under this view, the initial upward tongue tip motion, starting with the first vowel and moving to contact the hard palate on the way to a retroflex position, is under active muscular control, while the downward movement of the tongue tip, including the second contact with the hard palate, results from gravity and elasticity during tongue muscle relaxation. This sequence is reproduced using a three-dimensional computer simulation of human vocal tract biomechanics and differs greatly from other observed sequences for the same word, which employ multiple targeted speech motor actions. This outcome suggests that a goal of a speaker is to produce an entire sequence in a biomechanically efficient way at the expense of maintaining parity within the individual parts of the sequence.
authors: The New Zealand Institute for Language, Brain and Behavior, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
authors: Donald
authors: D
authors: Derrick
authors: Department of Computer Science, University of Saskatchewan, 176 Thorvaldson Building, 110 Science Place, Saskatoon, Saskatchewan, S7N5C9, Canada.
authors: Ian
authors: I
authors: Stavness
authors: Department of Linguistics, University of British Columbia, Totem Field Studios, 2613 West Mall, Vancouver, British Columbia, V6T1Z4, Canada.
authors: Bryan
authors: B
authors: Gick
mesh_terms: D000162:Acoustics; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D004548:Elasticity; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D007830:Larynx / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D009043:Motor Activity; D009068:Movement; D009119:Muscle Contraction; D017711:Nonlinear Dynamics; D021362:Palate, Hard / Q000502:physiology; D010700:Phonetics; D013061:Speech Acoustics; D013068:Speech Production Measurement; D013997:Time Factors; D014059:Tongue / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D014833:Voice Quality; D055815:Young Adult