Is a Stop Consonant Released When Followed by Another Stop Consonant

Many phonetics textbooks state that, in sequences of two stop consonants in English, the first stop is commonly unreleased. For nonhomorganic stop consonant sequences, this statement may be taken to imply that the (necessary) articulatory release of the first stop has no observable acoustic consequences. To examine this claim, we recorded sentences, produced by several native speakers of American English at a conversational rate, containing word-internal sequences of two nonhomorganic stops, either across a syllable boundary (e.g., cactus, pigpen), or in word-final position (e.g., act, sobbed) . Oscillograms of the critical words revealed that release bursts of the first stop occurred in the majority of tokens, except in those where the second stop was bilabial. The bursts were acoustically rather weak and difficult to detect by ear, which may account for their having been neglected in the literature. Instead of a simple Hreleased"-"unreleased" distinction, we propose a fiveway classification that makes use of articulatory, acoustic, perceptual, and contrastive phonetic criteria. INTRODUCTION In English, sequences of two nonhomorganic stop consonants are not uncommon. They occur across word boundaries (e. g., big dog, great game), across syllable boundaries within words (e.g., cactus, pigpen), and in wordfinal position (e.g, act, sobbed). Textbooks of English phonetics generally point out that the first stop in such sequences is commonly unreleased or unexploded. Some authors (e.g., Ladefoged, 1975, pp. 45, 49; MacKay, 1978, p. 166) say no more than that, while others (e. g., Abercrombie, 1967, p. 146; Catford, 1977, p. 222; Jones, 1956, p. 155; Kenyon, 1951, p. 47) are more explicit about the articulatory and acoustic events involved. Without further quali fication, the statement that the first stop in a two-stop sequence is unreleased may be misleading. If "release" is correctly interpreted as a strictly articulatory term, referring to the breaking of contact between two articulators that results in the release of overpressure built up behind the occlusion, the statement obviously cannot be true if the two stops have different places of articulation. In sequences of two *To appear in Phonetica. This is a revised and expanded version of a paper presented at the 101st Meeting of the Acoustical Society of America in Ottawa, Ontario, 18-22 May 1981. The research was supported by NICHD Grant HD01994 and BRS Grant RR05596 to Haskins Laboratories. We thank Arthur Abramson, Leigh Lisker, and Ignatius Mattingly for helpful comments on an earlier draft. TAIso Department of Linguistics, University of Connecticut, Storrs. [HASKINS LABORATORIES: Status Report on Speech Research SR-67/68 (1981)J