A model of speech motor control and supporting data: Influences of quantal effects

Abstract

A model of speech motor control is presented, along with examples of supporting data. In the model, segmental speech movements result from a process which plans a trajectory that passes through a sequence of phoneme-specific auditory goals. Some auditory goals are constrained by quantal relations between the vocal-tract area function and the resulting acoustics, as Stevens has proposed, and some are defined by quantal relations between motor commands and the area function, called biomechanical saturation effects. Both types of quantal relations make it possible to produce sounds that have relatively stable acoustic properties using somewhat imprecise motor commands. Therefore, quantal effects influence motor control strategies of individual speakers. They also influence sound patterns of languages, in that they help to define sounds such as the vowels /i/ and /a/ that occur frequently among languages of the world. Although there are other influences on speech motor control mechanisms and sound patterns, quantal effects are considered to be one of the defining characteristics of spoken language. [Work supported by NIDCD, NIH.]