Word-internal /t,d/ deletion in spontaneous speech: Modeling the effects of extra-linguistic, lexical, and phonological factors

The deletion of word-internal alveolar stops in spontaneous English speech is a variation phenomenon that has not previously been investigated. This study quantifies internal deletion statistically using a range of linguistic and extra-linguistic variables, and interprets the results within a model of speech production. Effects were found for speech rate and fluency, word form and word predictability, prominence, and aspects of the local phonological context. Results of the study are compared to results from the numerous studies of word-final alveolar stop deletion, internal deletion in laboratory speech, and also to another internal alveolar stop process, flapping. Our findings suggest that word-internal alveolar stop deletion is not a unitary phenomenon, but two different processes that arise at different points during speech production. In syllable codas, deletion results from cluster simplification to achieve gestural economy and is introduced during segment planning. In syllable onsets, deletion is one outcome of gradient lenition that results from gestural reduction during articulation. Phonetic variation occurs naturally in conversational speech, both within and across talkers. Indeed, to the extent that no two words are ever acoustically identical, variation occurs in all speech. Extensive research on variation has documented the influence of multiple factors on variation, including phonological context, properties of words, as well as a range of extra-linguistic variables, such as age, gender, and socioeconomic status. However, little is known about how factors relating to language usage influence variation, or how variation arises. In fact, for most phenomena, even information on the relative frequencies of specific words can be difficult to come by. In this study, we analyze one common variation phenomenon in spontaneous American English speech: the deletion of the alveolar stops 0t0 and 0d0 when they occur word-internally, that is, in any position other than the beginning or end of an orthographic word, as in stop, better, advice, or it’s. Our study examines The research reported here was supported by NIDCD grant DC004330 to Mark Pitt, Keith Johnson, and Elizabeth Hume. Our thanks to Mark Pitt, Keith Johnson, William Labov, David Sankoff, two anonymous reviewers, and numerous participants of NWAV02 for useful comments and constructive feedback that helped us develop the article. Language Variation and Change, 18 (2006), 55–97. Printed in the U.S.A. © 2006 Cambridge University Press 0954-3945006 $9.50 DOI: 10.10170S0954394506060042