Within the human motor repertoire, speech production has a uniquely high level of spatiotemporal complexity. The production of running speech comprises the traversing of spatial positions with precisely coordinated articulator movements to produce 10 - 15 sounds/s. How does the brain use auditory feedback, namely the self-perception of produced speech sounds, in the online control of spatial and temporal parameters of multisyllabic articulation? This question has important bearings on the organizational principles of sequential actions, yet its answer remains controversial due to the long latency of the auditory feedback pathway and technical challenges involved in manipulating auditory feedback in precisely controlled ways during running speech. In this study, we developed a novel technique for introducing time-varying, focal perturbations in the auditory feedback during multisyllabic, connected speech. Manipulations of spatial and temporal parameters of the formant trajectory were tested separately on two groups of subjects as they uttered "I owe you a yo-yo." Under these perturbations, significant and specific changes were observed in both the spatial and temporal parameters of the produced formant trajectories. Compensations to spatial perturbations were bidirectional and opposed the perturbations. Furthermore, under perturbations that manipulated the timing of auditory feedback trajectory (slow-down or speed-up), significant adjustments in syllable timing were observed in the subjects' productions. These results highlight the systematic roles of auditory feedback in the online control of a highly over-learned action as connected speech articulation and provide a first look at the properties of this type of sensorimotor interaction in sequential movements.

Associate Professor, Department of Linguistics, Brown University. +Associate Professor, Department of Psychology and Social Relations, Harvard University. tAssistant Professor, Department of Psychology, Northeastern University. ** Assistant Professor, Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires, Argentina. ++Assistant Professor of Communicative Disorders, Emerson College. #Staff Member, Bolt Beranek and Newman, Inc.

Academic and Research Staff Prof. K.N. Stevens, Prof. J. Allen, Prof. M. Halle, Prof. S.J. Keyser, Prof. V.W. Zue, A. Andrade1 1 , Dr. D. Bradley 1 , Dr. Martha Danly12 , Dr. F. Grosjean1 3 , Dr. S. Hawkins 14 , Dr. R.E. Hillman 5 , E.B. Holmberg , Dr. A.W.F. Huggins , C. Hume, Dr. H. Kawasaki, Dr. D.H. Klatt, Dr. L.S. Larkey, Dr. John Locke 18, Dr. B. Lyberg"1 , Dr. J.I. Makhou117, Dr. E. Maxwell, Dr. L. Menn1 9, Dr. P. Menyuk 20 , Dr. J.L. Miller 13, Dr. J.M. Pardo Munoz 11, Dr. J.S. Perkell, Dr. P.J. Price, Dr. S. Shattuck-Hufnagel, S.-Q. Wang", T. Watanabe1 1

A two-part experiment on protrusion movements of the lower lip for the vowel /u/ was conducted to investigate: (1) the production of ‘troughs’, i.e., diminution of lip protrusion during the intervocalic consonant in /uCu/ utterances, and (2) ‘time locking’, that is, movement onset at a fixed interval prior to onset of voicing of /u/, regardless of the number of ‘neutral’ consonants in /VunroundedCnu/ utterances.