Introduction

There are two durational effects often cited as evidence for very different models of prosodic constituency in English. The first is known variously as “final lengthening,” “pre-boundary lengthening,” or “pre-pausal lengthening” (e.g. Oiler 1973; Klatt 1975; Cooper and Paccia-Cooper 1980). As the last name suggests, this effect is usually interpreted as a durational correlate of the sort of disjuncture that can cause a momentary cessation of speech. The second durational effect has no similar unified set of labels, but it might be called “stresstimed shortening” since it belongs to a class of effects that have been interpreted as indications of a tendency toward isochronous spacing of prosodically strong syllables; a stressed syllable in a polysyllabic word or stress foot is compressed in order to make the overall duration of its word or stress foot closer to that of a contrasting monosyllable (e.g. Huggins 1975; Fowler 1977).

The two effects are similar in that both involve an apparent adjustment of syllable durations which is dependent on some notion of constituency. In the first case, a syllable is lengthened because of its position near to the edge of some constituent, and in the second it is shortened because of the length of a constituent defined by adjacent peaks at some prosodic level. The two effects differ radically, however, in the type of constituency that is implicit in their interpretations. Final lengthening implies a constituent that has well-defined edges; the lengthening occurs before a boundary that could be followed by a pause. But this constituent need not have a phonological head; its internal prosodic structure could be completely flat.