Effects of obstruent consonants on fundamental frequency at vowel onset in English.

When a vowel follows an obstruent, the fundamental frequency in the first few tens of milliseconds of the vowel is known to be influenced by the voicing characteristics of the consonant. This influence was re-examined in the study reported here. Stops, fricatives, and the nasal /m/ were paired with the vowels /i,a/ to form CVm syllables. Target syllables were embedded in carrier sentences, and intonation was varied to produce each syllable in either a high, low, or neutral pitch environment. In a high-pitch environment, F0 following voiceless obstruents is significantly increased relative to the baseline /m/, but following voiced obstruents it closely traces the baseline. In a low-pitch environment, F0 is very slightly increased following all obstruents, voiced and unvoiced. It is suggested that for certain pitch environments a conflict can occur between gestures corresponding to the segmental feature [stiff vocal folds] and intonational elements. The results are different acoustic manifestations of [stiff] in different pitch environments. The spreading of the vocal folds that occurs during unvoiced stops in certain contexts in English is an enhancing gesture, which aids the resolution of the gestural conflict by allowing the defining segmental gesture to be weakened without losing perceptual salience.