Correspondence is a relation between one representation and another (McCarthy & Prince 1993, 1994, 1995). This relationship may be between an underlying or lexical representation and a surface representation, that is: Input–Output forms; or between surface forms such as a reduplicant and its base (McCarthy & Prince 1995) or other derivationally related pairs (see for example Benua 1995, McCarthy 1995, Kenstowicz 1996) – i.e. Output–Output. Correspondence constraints over related words in a paradigm ensure uniformity within the paradigm. In earlier theories this effect was ensured by the Strict Cycle Constraint, which forbade structure-changing operations except in immediately derived environments and thus ensured that most of the base word stayed the same in derivation. In this paper we show that correspondence between derivationally related output forms (Benua 1995) is essential for the proper analysis of vowel length in Warray, a language of Northern Australia spoken near Darwin, and superior to an account making use of cyclicity. Correspondence constraints ensuring identity between output forms explain the pattern of vowel length in nouns, predicting both where long vowels occur as well as the apparently anomalous appearance of short vowels where long vowels might be expected.

Athabaskan languages display a remarkable cross-language similarity, yet at the same time the languages of this family differ from each other in restricted ways. This unity and variety provide a useful laboratory for phonological and morphological research. In this paper, we suggest that a certain case of unity which has been analysed as phonologically and morphologically motivated requires a purely morphological analysis.

The case in question is the well-known verbal disyllabic minimality requirement, which has been variously analysed as satisfaction of a disyllabic verb template (Slave; Rice 1990), satisfaction of a monosyllabic prefix-based portmanteau ‘stem’ (Navajo; McDonough 1990, 1996) or the result of stray consonant syllabification in the Minimal Word domain in verbs (Ahtna; Causley 1994). However, when data from other languages of the family are brought into the picture, a different, family-wide analysis suggests itself.

Prosodification processes like syllabification and foot parsing are often limited to a particular morphological constituent; i.e. they do not apply across a morpheme boundary. Prince & Smolensky (1993) present a new interpretation of this phenomenon which identifies the edge of a morphological constituent, rather than the morphological constituent as such, as opaque to prosodification. On their view, the morphological boundedness of processes that erect metrical structure reflects the desire for a grammatical constituent edge to coincide with the edge of a prosodic constituent, formalised as ALIGN(GCat-Edge 1, PCat-Edge 1) in their theory. Since prosodification across a morpheme boundary results in a mismatch between the edges of a prosodic and a morphological constituent, it is blocked whenever alignment is obeyed.

In this paper I claim that not only prosodification processes but also feature spreading is subject to pressure from an alignment constraint, and so is avoided. The case in point is dorsal fricative assimilation in Modern Standard German. Dorsal fricative assimilation does not apply across a compound boundary or to the dorsal fricative of the diminutive suffix -chen, which, though morphologically a suffix, is prosodically a separate phonological word of German (Noske 1990, Iverson & Salmons 1992, Borowsky 1993, Wiese 1996). Bringing Itô & Mester's (in press) notion of crisp alignment to bear on the analysis, I argue that the application of fricative assimilation is constrained by CRISPEDGE(PrWd), which requires the prosodic word to have sharply defined boundaries. Since spreading from a word-final back vowel to the initial dorsal of the following word results in a blurred word edge, it is ruled out, because CRISPEDGE(PrWd) is ranked higher than the constraint governing spreading.

Linguistic sound systems necessarily possess contrastive values that are sufficiently distinct from one another that their individual characters may be learned by the listener. In this way, any given value in any given system fulfils its functional role of rendering forms distinct which differ in meaning. Articulatory, aerodynamic, acoustic and auditory constraints serve to mediate between such sound–meaning correspondences in non-trivial ways. Indeed, if it can be shown that the sound patterns of language are in part explainable by these physical systems, then students of linguistic sound systems would do well to study in detail the phonetic base. Consider an example case. Laryngeal gestures and supralaryngeal gestures are by and large articulatorily independent of each other. Thus, for example, a voiceless aspirated stop consists of an oral occlusion, cued by silence, as well as an articulatorily independent laryngeal abduction, cued by broadband noise. Were the phonetic realisation of these two gestures strictly simultaneous, the cues signalling the laryngeal abduction would not be perceived as such by the listener (*[ot]). A listener can tell that there is no voicing, but cannot recover more specific information regarding the state of the glottis during oral closure. Stated simply, the full closure here reduces the acoustic output to zero. With zero acoustic energy, no source information other than silence is transmitted to the listener. However, upon staggering the two gestures, the otherwise obscured information is rendered salient.

Certain kinds of complex phenomena serve as testing and proving grounds in phonology as theories develop and change. Cases of what I will call CONFLICTING DIRECTIONALITY, exemplified by the stress pattern in Selkup (Ostyak-Samoyed) in (1), constitute one such phenomenon (Halle & Clements 1983, Idsardi 1992). This pattern, first discussed for Eastern Cheremis by Kiparsky (1973) (from Itkonen 1955), has informed all major theories of stress (Hayes 1981, 1995, Prince 1983, Halle & Vergnaud 1987, Kenstowicz 1995, Halle & Idsardi 1995, among others). Descriptively, in Selkup the rightmost heavy (CVV) syllable receives the stress (1a), but if the word contains no heavy syllables, it is the leftmost syllable which is stressed (1b). The term CONFLICTING DIRECTIONALITY describes this elsewhere relationship between the right and left edges of a word. No theory of stress is complete if it cannot account for this pattern.