The study of vowel quality has traditionally been based on single-point formant frequency measurements. There is considerable evidence now acknowledging spectral change as an essential part of the vowel system. Previous descriptions of Singapore English vowels have generally been impressionistic, with few offering detailed analysis of vowel quality and based on single-point formant frequency measurements at that. Collectively, they converge on the observations that the target monophthong pairs /i, ɪ/, /u, ʊ/, /ɔ, ɒ/, /ɑ, ʌ/, /æ, ɛ/ and /ɜ, ə/ are each realized as conflated single vowel sounds and the target diphthongs /ɛi/, /ɛə/ and /oʊ/ are monophthongized, with some overlap with the monophthongs listed above. This study analyzes the inherent spectral change of Singapore English vowels based on a dataset from the National Speech Corpus and examines possible contrast in duration between its tense-lax vowel pairs with the aim of providing an update on the description of its vowel system. Contrary to past conclusions, the present study finds no clear conflation of the monophthong pairs /i, ɪ/, /u, ʊ/, /ɔ, ɒ/, /ɑ, ʌ/ and /ɜ, ə/, or the reduction of /ɛə/. However, results do show the conflation of /æ/ and /ɛ/, and the monophthongization of /ɛi/ and /oʊ/.

The trap vowel /æ/ is known to display a complex variable duration in many English dialects, but this phenomenon is understudied in Australian English. Previous analyses suggest that trap duration is sensitive to the effects of following phonetic environments in complex ways, but that a lexically specific effect may also operate in determining duration. This study aims to investigate phonetic and lexical effects through an acoustic analysis of trap duration in Australian English. Speakers from a range of areas in Sydney that vary in their ethnic and linguistic diversity produced the trap vowel in select phonetic contexts. Results suggest that trap exhibits a complex hierarchy of durations which are conditioned by the characteristics of the following coda, as well as a notably long duration in the affective adjectives mad and sad compared to other words with coda /d/ that were tested. However, these effects were found to be relatively less pronounced among speakers from more ethnically and linguistically diverse regions of Sydney. This may be attributed to high levels of language and dialect contact occurring in more diverse areas resulting in a gradual reduction in the degree of trap durational variability.

The aim of this study was to examine spoken Namibian English by investigating how multilingual Namibian speakers produce vowel durations in pre-lenis and pre-fortis positions, and how those vowel durations compare to British English vowel durations in the same words. In British English and most other English varieties, vowel duration is affected by the voicing of the following consonant, so that vowels preceding phonologically voiced consonants are longer (pre-lenis lengthening) and vowels preceding phonologically voiceless consonants are shorter (pre-fortis clipping). The production data was collected using orthographic stimuli that were monosyllabic English words with voiced and voiceless final consonants after the target vowels. The data were collected from 14 multilingual Namibian English speakers. The vowel durations produced by the speakers in pre-lenis and pre-fortis position were first compared to each other and then to those produced by nine British English speakers in an earlier study. The results showed that the pre-lenis vowels were clearly longer than the pre-fortis vowels, and there were no differences between Namibian and British English vowel durations in most of the tested words. The results offer new insights into the realization of vowel duration in pre-lenis and pre-fortis positions in Namibian English.

Using ten English adjectives, this study tests the hypothesis that the vowels in adjectives in predicative constructions are longer than those in attributive constructions in spoken conversation. The analyses considered a number of factors: occurrence before a pause, lexical adjective, vowel identity, probability given surrounding words, and others. Two sets of statistical techniques were used: a Mixed-effects model and the Random Forest Analysis based on Conditional Inference Trees (CIT). Both analyses showed strong effects of predicative vs. attributive constructions and individual lexical adjectives on vowel duration in the predicted direction, as well as effects of many of the phonological variables tested. The results showed that the longer duration in the predicative construction is not due to lengthening before a pause, though it is related to whether the adjective is internal or final in the predicative construction. Nor is the effect attributable solely to the probability of the occurrence of the adjective; rather construction type has to be taken into account. The two statistical techniques complement each other, with the Mixed-effects model showing very general trends over all the data, and the Random Forest / CIT analysis showing factors that affect only subsets of the data.