Adaptation of voicing: effects of ear presentation and acoustic energy variables

Abstract

Although empirical evidence from the selective adaptation paradigm supports peripheral and central processes of phonetic variables, little research exists on levels of perceptual processing of acoustic energy variables. The purpose of this investigation was to determine the effects of ear presentation, intensity, and number of repetitions of adaptors varying in voice onset time (VOT) on changes in stimulus rating of boundary and non-boundary stimuli. Subjects rated stimuli varying in VOT between 15–45 ms before and after periods of stimulus repetition. The number of stimulus repetitions during each of 28 trials was either 4, 16, or 85, and the intensity of the stimulus was either 50 or 70 dB SPL. The major findings were as follows: (1) evidence of a strong monaural component for intensity and ear effect was obtained for only the voiced stimulus; (2) monaural effects of the voiced stimulus appeared for both boundary and non-boundary stimuli; and (3) the repetition effect supported a higher level process in adaptation to voicing. The monaural effects of the voiced stimulus support a fatigue model; whereas the effects of number of stimulus repetitions and the asymmetries of acoustic energy variables for the voiced and voiceless adaptors suggest a more complicated process in adaptation to speech than that accounted for in models of feature detection and response contrast.