Property detectors for bursts and transitions in speech perception

Abstract

A series of adaptation experiments was conducted on students to investigate the role of initial noise bursts and transitions as cues to place of articulation in stop consonants. A test continuum was constructed consisting of 14 synthetic stimuli in which the transitions of formant 2 and formant 3 were systematically varied to range along the [b d g] phonetic dimension. The adapting stimuli consisted of full-cue stimuli in which place of articulation was signaled by burst as well as transitions; partial-cue stimuli in which place was signaled by transitions only; and conflicting-cue stimuli in which the burst frequency signaled 1 phonetic dimension (e.g., [d]), whereas the transitions signaled another (e.g., [g]). Adaptation with either the partial- or full-cue stimuli produced significant shifts in phonetic boundaries for the test continuum, with the full-cue stimuli producing a slightly greater boundary shift. The conflicting-cue stimuli produced no significant shifts in adaptation. Adaptation effects were a function of the acoustic attributes of the stimulus independent of the phonetic label given the stimulus by the subject. These results were interpreted in terms of a model that postulates a set of integrated properties characterized by the short-term acoustic spectrum sampled at the abrupt amplitude discontinuity at consonantal release, and a set of simple properties consisting of individual attributes of the test stimuli such as burst frequency.