Amplitude Rise Time Does Not Cue the /bɑ/–/wɑ/ Contrast for Adults or Children

Abstract

Previous research has demonstrated that children weight the acoustic cues to many phonemic decisions differently than do adults and gradually shift those strategies as they gain language experience. However, that research has focused on spectral and duration cues rather than on amplitude cues. In the current study, the authors examined amplitude rise time (ART; an amplitude cue) and formant rise time (FRT; a spectral cue) in the /b/-/w/ manner contrast for adults and children, and related those speech decisions to outcomes of nonspeech discrimination tasks. Twenty adults and 30 children (ages 4-5 years) labeled natural and synthetic speech stimuli manipulated to vary ARTs and FRTs, and discriminated nonspeech analogs that varied only by ART in an AX paradigm. Three primary results were obtained. First, listeners in both age groups based speech labeling judgments on FRT, not on ART. Second, the fundamental frequency of the natural speech samples did not influence labeling judgments. Third, discrimination performance for the nonspeech stimuli did not predict how listeners would perform with the speech stimuli. Even though both adults and children are sensitive to ART, it was not weighted in phonemic judgments by these typical listeners.