In many languages the issue arises as to whether an onglide patters as part of the syllable onset or forms the first part of a (rising) diphthong with the immediately following vowel. If it is part of the syllable onset, the structure of a CGV syllable would be as in (1), but if it forms the first part of a diphthong the structure of a CGV syllable could either be as in (2a) with a monomoraic diphthong (where the glide is ‘co-moraic’ with the following vowel) or as in (2b) with a bimoraic diphthong (C = consonant, G = glide, V = vowel, μ = mora, and σ = syllable).

In early autosegmental studies certain segments were specially marked with a ‘star’ diacritic. These starred segments had a priority association; only in a later stage of the derivation were other segments associated. Starred associations were resistant to modification by subsequent rules: ‘the point is to preserve the prominence of the star’ (Goldsmith 1979: 129). An associated tone had as its phonetic exponent a high or low pitch occurring approximately at the same time as the associated item(s) on the phoneme tier, usually a vowel.

An interesting feature of many Bantu languages is the presence of what have been called ‘prenasalised consonants’-these are typically sounds that might be interpreted as a sequence of nasal + stop, but which behave in many respects like single segments:

In current phonological feature theories, the behaviour of glottals poses serious problems for their representation. The special status of / h / and /? / which are often transparent to vowel harmony processes (cf. Steriade 1987; McCarthy 1991, forthcoming; Stemberger 1993), has led to the hypothesis that, at least in some languages, they lack a place node. The representation of ejectives and implosives, though, is very rarely discussed in the literature. On phonetic grounds, the main difference between plain stops and ejectives and implosives is the airstream mechanism used during their realisation, the former having a pulmonic egressive airstream while the latter involve a supplementary glottal constriction, which may accompany either egressive airflow, as in ejectives, or ingressive, as in implosives.

The underlying system of consonants and vowels in Brazilian Portuguese (henceforth BP), together with the lexical and word-level phonological rules and the interactions between them, has been studied in great detail (see e.g. Harris 1974; Lopez 1979; Redenbarger 1981; Quicoli 1990). The detailed knowledge we possess in this area of BP phonology makes the language an excellent test case for evaluating theoretical innovations, especially since genuine descriptive and explanatory progress can only be achieved by virtue of improved theoretical models. The discussion in this paper will focus on the rules of Vowel Harmony (henceforth VH), Truncation, Neutralisation and Vowel Lowering in verbs (henceforth VL), for which a non-linear analysis will be proposed. One of the purposes of this paper is to show that a treatment of the BP vowel alternations in non-linear terms yields an elegant and explanatory description of a substantial part of the BP phonological component. Another goal is to present the theoretically relevant aspects of the BP facts. It will be argued that aperture distinctions in BP are advantageously represented by a single phonetic parameter, which will not only dispense with the features [high] and [low], but also with [ATR] or [tense], which have been frequently used to distinguish the two series of BP mid vowels. Also, further evidence will be provided in favour of the hypothesis advanced by a number of phonologists (see Clements 1991a; Odden 1991) that aperture features should be represented as constituents in the vocalic feature tree.