Variation in the realization of glottalization in normal speakers

Glottalized voice quality has been observed consistently in normal utterances in a variety of locations, including as an allophone of voiceless stops (in e.g., Hat,eld, butler), in word-initial vowels at intonation phrase onsets and at pitch accents, and at the ends of utterances. In this study of American English, we examine glottalizations at phrase boundaries which are medial or "nal in an utterance. Tokens are characterized as examples of aperiodicity (irregular periods), creak (lowering of fundamental frequency with near-total damping), diplophonia (alternation in the shape, amplitude, or duration of successive periods) and a fourth category, glottal squeak. Findings include (a) a wide range in the rates of glottalization and in preferred acoustic characteristics across individual speakers, (b) a higher rate of glottalization on words at the ends of utterances than on words at the ends of utterance-medial intonational phrases, and (c) a higher rate of glottalization at the boundaries of full intonational phrases than at intermediate intonational phrases. These patterns will need to be accounted for in any comprehensive treatment of surface phonetic variation in speech. ( 2001 Academic Press