Physical principles behind quantal relations.

Abstract

A distinctive contrast can be defined by a quantal relation between an articulatory parameter and an acoustic parameter. It is postulated that there are two sources of quantal relations. Aeromechanical interactions arise because the nature of the interaction of airflow with the compliant mechanical structures of the vocal tract can change abruptly as an articulatory parameter changes continuously. As a result, the nature of the generated acoustic source changes abruptly. Acoustic resonator coupling results from the fact that the vocal tract, together with adjacent structures, can create several cavities that can be coupled and uncoupled, resulting in a transfer function that can show an abrupt discontinuity as a consequence of the rapid movement of a zero. These two principles lead to a natural division of the distinctive features into two groups, articulator free and articulator bound. Because the features in the two groups are defined by different physical principles, relations among the features are quite different: the articulator-free features, being based on aerodynamic conditions in the vocal tract, are constrained hierarchically, while articulator-bound features have fewer constraints. The natural constraints among the features are such that the featural representation of a segment is rather sparse.