Burst spectrum as a cue for the stop voicing contrast in American English

Abstract

Voicing contrasts in stop consonants are expressed by a constellation of acoustic cues. This study focused on a spectral cue present at burst onset in American English labial and coronal stops. Spectral shape was examined for word-initial, prevocalic stops of all three places of articulation in a laboratory production study and a large corpus of continuous read speech. Voiceless labial and coronal stops were found to have greater energy at higher frequencies in comparison to homorganic voiced stops, a difference that could not be attributed to aspiration in the voiceless stops or modal phonation in the voiced, while no consistent effect was found for dorsal stops. This pattern was found with various methods of spectral estimation (time-averaged and multitaper spectra) and measures of spectral energy concentration (center of gravity and spectral peak) for both linear and auditorily based frequency scales. Perceptual relevance of the spectral cue was tested in laboratory and online experiments with continua created by crossing burst shape and voice onset time. A trading relation was observed such that voiceless identifications were more likely for tokens with higher frequency bursts. Goodness ratings indicated that burst spectrum influences category typicality for voiceless stops even when voice onset time is unambiguous.