Nonlinear Dynamical Systems in Speech Perception and Production

Abstract

Research examining the nonlinear, dynamical-systems aspects of speech production and perception is reviewed. Examples are provided from studies of phonation, speech respiration, vocal tract acoustics, speech gestures, and auditory-phonetic perception. Results support a conclusion that nonlinear, dynamical system behaviors and principles are represented in speech production and perception at several levels of system behavior. The results are interpreted as suggesting that the communicative distinctions in speech are represented in task-relevant, order parameters which are preserved over a wide range of sets of task-irrelevant, control parameters. The control parameters, in turn, define the domains of behavior for each of the relevant acoustic, biological, or psychological systems. More specifically, it is proposed that speech order parameters may be understood in terms of collective variables defined, in production, over the degrees of, and opening/closing rates of, the vocal tract and, in perception, over the rates, amounts, and relative phases of the broad-band temporal modulations in speech signals.