The trough effect: implications for speech motor programming.

While the existence of the trough effect is unquestioned, its theoretical significance is unknown. A multifaceted instrumental approach - spectrographic, cineradiographic, and vocal tract modeling - was used to document the trough effect in open (V.CV) and closed (VC.V) syllable forms using a symmetrical vowel context surrounding labial stops. Collectively, the results document the trough phenomeon as a momentary deactivation of tongue and/or lip movement after V1 and continuing into the stop closure. This empirical event suggests a segment-by-segment activation pattern as opposed to a diphthongal vowel-to-vowel trajectory with an independent and superimposed consonantal gesture. Quantitative models of VCV coarticulation must incorporate the trough effect in order to more effectively capture the kinematic properties of speech. Copyright (C) 2002 S. Karger AG, Basel.