aperture (n.)

A term used in various models of NON-LINEAR PHONOLOGY to handle CONTRASTS involving OPENNESS of ARTICULATION. In PARTICLE PHONOLOGY, for example, aperture is a PRIVATIVE feature (particle) representing openness, and symbolized by [a]. Differences in vowel height are characterized by combinations of aperture particles: for example, combining [a] with palatal [i] results in a relatively open PALATAL vowel, such as [e]. In a CONSTRICTION model of phonology, aperture refers to the degree of constriction imposed on a VOCOID (a VOWEL or a GLIDE), which dominates vowel height features. It is one of the two main parameters of classification for vocoids (the other being PLACE). The superordinate node is called the aperture node. In some approaches, CONTOUR segments have been analyzed as sequences of aperture nodes. A threefold classification is recognized: the total absence of oral airflow (as in oral STOPS), a degree of aperture sufficient to produce air turbulence (as in FRICATIVES), and a degree of aperture insufficient to produce turbulence (as in oral SONORANTS).