Five Decades of Research in Speech Motor Control: What Have We Learned, and Where Should We Go From Here?

Abstract

The author presents a view of research in speech motor control over the past 5 decades, as observed from within Ken Stevens's Speech Communication Group (SCG) in the Research Laboratory of Electronics at MIT. The author presents a limited overview of some important developments and discoveries. The perspective is based largely on the research interests of the Speech Motor Control Group (SMCG) within the SCG; thus, it is selective, focusing on normal motor control of the vocal tract in the production of sound segments and syllables. It also covers the particular theories and models that drove the research. Following a brief introduction, there are sections on methodological advances, scientific advances, and conclusions. Scientific and methodological advances have been closely interrelated. Advances in instrumentation and computer hardware and software have made it possible to record and process increasingly large, multifaceted data sets; introduce new paradigms for feedback perturbation; image brain activity; and develop more sophisticated, computational physiological and neural models. Such approaches have led to increased understanding of the widespread variability in speech, motor-equivalent trading relations, sensory goals, and the nature of feedback and feedforward neural control mechanisms. Some ideas about important future directions for speech research are presented.