Singapore English consonant clusters undergo phonological processes that exhibit variation and opacity. Quantitative evidence shows that these patterns are genuine and systematic. Two main conclusions emerge. First, a small set of phonological constraints yields a typological structure (T-order) that captures the quantitative patterns, independently of specific assumptions about how the grammar represents variation. Second, the evidence is consistent with the hypothesis that phonological opacity has only one source: the interleaving of phonology and morphology.

This paper reconciles the standpoint that language users do not aim at improving their sound systems with the observation that languages seem to improve their sound systems. If learners optimise their perception by gradually ranking their cue constraints, and reuse the resulting ranking in production, they automatically introduce a prototype effect, which can be counteracted by an articulatory effect. If the two effects are of unequal size, the learner will end up with a sound system auditorily different from that of her language environment. Computer simulations of sibilant inventories show that, independently of the initial auditory sound system, a stable equilibrium is reached within a small number of generations. In this stable state, the dispersion of the sibilants of the language strikes an optimal balance between articulatory ease and auditory contrast. Crucially, these results are derived within a model without any goal-oriented elements such as dispersion constraints.

When a medial consonant cluster is simplified by deletion or place assimilation, the first consonant is affected, but never the second one: /patka/ becomes [paka] and not *[pata]; /panpa/ becomes [pampa] and not [panta]. This article accounts for that observation within a derivational version of Optimality Theory called Harmonic Serialism. In Harmonic Serialism, the final output is reached by a series of derivational steps that gradually improve harmony. If there is no gradual, harmonically improving path from a given underlying representation to a given surface representation, this mapping is impossible in Harmonic Serialism, even if it would be allowed in classic Optimality Theory. In cluster simplification, deletion or Place assimilation is the second step in a derivation that begins with deleting Place features, and deleting Place features improves harmony only in coda position.

It has been proposed that Tashlhiyt is a language which allows any segment, including obstruents, to be a syllable nucleus. The most striking and controversial examples taken as arguments in favour of this analysis involve series of words claimed to contain only obstruents. This claim is disputed in some recent work, where it is argued that these consonant sequences contain schwas that can be syllable nuclei. This article presents arguments showing that vowelless syllables do exist in Tashlhiyt, both at the phonetic and phonological levels. Acoustic, fibrescopic and photoelectroglottographic examination of voiceless words (e.g. [tkkststt]) provide evidence that such items lack syllabic vocalic elements. In addition, two types of phonological data, metrics and a spirantisation process, are presented to show that in this language schwa is not a segment which can be independently manipulated by phonological grammar and which can be referred to the syllable structure.