School of Languages and Linguistics - Research Publications
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ItemProsodically Conditioned Consonant Duration in Djambarrpuyŋu.(SAGE Publications, 2019-03-01)Cross-linguistically, segments typically lengthen because of proximity to prosodic events such as intonational phrase or phonological phrase boundaries, a phrasal accent, or due to lexical stress. Australian Indigenous languages have been claimed to operate somewhat differently in terms of prosodically conditioned consonant lengthening and strengthening. Consonants have been found to lengthen after a vowel bearing a phrasal pitch accent. It is further claimed that this post-tonic position is a position of prosodic strength in Australian languages. In this study, we investigate the effects of proximity to a phrasal pitch accent and prosodic constituent boundaries on the duration of stop and nasal consonants in words of varying lengths in Djambarrpuyŋu, an Australian Indigenous language spoken in northeast Arnhem Land, Northern Territory, Australia. Our results suggest that the post-tonic consonant position does not condition longer consonant duration compared with other word-medial consonants, with one exception: Intervocalic post-tonic consonants in disyllabic words are significantly longer than word-medial consonants elsewhere. Therefore, it appears that polysyllabic shortening has a strong effect on segment duration in these data. Word-initial position did not condition longer consonant duration than word-medial position. Further, initial consonants in higher-level prosodic domains had shorter consonant duration compared with domain-medial word-initial consonants. By contrast, domain-final lengthening was observed in our data, with word-final nasals preceding a pause found to be significantly longer than all other consonants. Taken together, these findings for Djambarrpuyŋu suggest that, unlike other Australian languages, post-tonic lengthening is not a cue to prosodic prominence, whereas prosodic domain-initial and -final duration patterns of consonants are like those that have been observed in other languages of the world.
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ItemNo Preview AvailableAcoustic analysis of the effects of sustained wakefulness on speech(ACOUSTICAL SOC AMER AMER INST PHYSICS, 2010-12)Exposing healthy adults to extended periods of wakefulness is known to induce changes in psychomotor functioning [Maruff et al. (2005). J. Sleep Res. 14, 21-27]. The effect of fatigue on speech is less well understood. To date, no studies have examined the pitch and timing of neurologically healthy individuals over 24 h of sustained wakefulness. Therefore, speech samples were systematically acquired (e.g., every 4 h) from 18 healthy adults over 24 h. Stimuli included automated and extemporaneous speech tasks, sustained vowel, and a read passage. Measures of timing, frequency and spectral energy were derived acoustically using PRAAT and significant changes were observed on all tasks. The effect of fatigue on speech was found to be strongest just before dawn (after 22 h). Specifically, total speech time, mean pause length, and total signal time all increased as a function of increasing levels of fatigue on the reading tasks; percentage pause and mean pause length decreased on the counting task; F4 variation decreased on the sustained vowel tasks /a:/; and alpha ratio increased on the extemporaneous speech tasks. These findings suggest that acoustic methodologies provide objective data on central nervous system functioning and that changes in speech production occur in healthy adults after just 24 h of sustained wakefulness.
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ItemNo Preview AvailableReliability, stability, and sensitivity to change and impairment in acoustic measures of timing and frequency(Elsevier Inc., 2011)Assessment of the voice for supporting classifications of central nervous system (CNS) impairment requires a different practical, methodological, and statistical framework compared with assessment of the voice to guide decisions about change in the CNS. In experimental terms, an understanding of the stability and sensitivity to change of an assessment protocol is required to guide decisions about CNS change. Five experiments (N=70) were conducted using a set of commonly used stimuli (eg, sustained vowel, reading, extemporaneous speech) and easily acquired measures (eg, f0–f4, percent pause). Stability of these measures was examined through their repeated application in healthy adults over brief and intermediate retest intervals (ie, 30 seconds, 2 hours, and 1 week). Those measures found to be stable were then challenged using an experimental model that reliably changes voice acoustic properties (ie, the Lombard effect). Finally, adults with an established CNS-related motor speech disorder (dysarthria) were compared with healthy controls. Of the 61 acoustic variables studied, 36 showed good stability over all three stability experiments (eg, number of pauses, total speech time, speech rate, f0–f4). Of the measures with good stability, a number of frequency measures showed a change in response to increased vocal effort resulting from the Lombard effect challenge. Furthermore, several timing measures significantly separated the control and motor speech impairment groups. Measures with high levels of stability within healthy adults, and those that show sensitivity to change and impairment may prove effective for monitoring changes in CNS functioning.
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ItemCan you t[ae]ll I'm from M[ae]lbourne? An overview of the DRESS and TRAP vowels before /l/ as a regional accent marker in Australian English(John Benjamins Publishing, 2017-01-01)This study gives an overview of the merger of the DRESS and TRAP vowels before laterals, which occurs for some speakers of Australian English in the state of Victoria (in the south-east of the country), as well as in some other varieties of English. Research on this phenomenon in Australian English has been preliminary to date, but has uncovered some general tendencies in distribution, as well as possible motivators for actuation and spread of the change. The aim of this paper is to describe and orient the phenomenon in the context of English worldwide, and while we work with some illustrative experimental data, our aim is not to provide a detailed quantitative sociophonetic perspective here. This paper further aims to illustrate the extent of the variability seen in the Australian English community with respect to ongoing change.
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ItemNo Preview AvailableThe impact of task automaticity on speech in noise(Elsevier Science, 2014)In the control of skeleto-motor movement, it is well established that the less complex, or more automatic a motor task is, the less variability and uncertainty there is in its performance. It was hypothesized that a similar relationship exists for integrated cognitive-motor tasks such as speech where the uncertainty with which actions are initiated may increase when the feedback loop is interrupted or dampened. To investigate this, the Lombard effect was exploited to explore the acoustic impact of background noise on speech during tasks increasing in automaticity. Fifteen healthy adults produced five speech tasks bearing different levels of automaticity (e.g., counting, reading, unprepared monologue) during habitual and altered auditory feedback conditions (Lombard effect). Data suggest that speech tasks relatively free of meaning or phonetic complexity are influenced to a lesser degree by a compromised auditory feedback than more complex paradigms (e.g., contemporaneous speech) on measures of timing. These findings inform understanding of the relative contribution speech task selection plays in measures of speech. Data also aid in understanding the relationship between task automaticity and altered speech production in neurological conditions where dual impairments of movement and cognition are observed (e.g., Huntington’s disease, progressive aphasia).
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ItemAn Investigation of the /el/-/ae l/ Merger in Australian English: A Pilot Study on Production and Perception in South-West Victoria(Taylor & Francis (Routledge), 2014-01-01)This exploratory study looks at evidence of merger between /el/ and /æl/ in Australian English, and the possible relationship between production and perception that might be involved in such a process. This merger appears to occur primarily in Victoria, although its regional distribution within that state still requires investigation. The phenomenon appears to be motivated by the interaction of three different phonetic processes: increasing lateral velarization; increasing vowel lowering; and misperception/misparsing of the phonetic signal. We focus here on the behaviour of a sample of native speakers from Warrnambool, a regional township in south-west Victoria. Given evidence that some speakers merge the vowels in /el/ and /æl/ while others do not, our participants are categorized as maintainers (those who keep /el/–/æl/ distinct) and combiners (those who merge /el/–/æl/), and we compare how the groups process /el/–/æl/ in perception. Overall results point to an association, according to category, between listeners' own production and perception of /el/–/æl/ in an identification task, although individual variability is also evident and needs to be understood.
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ItemLocus equations and coarticulation in three Australian languages(Nature Research, 2015-02-01)Locus equations were applied to F2 data for bilabial, alveolar, retroflex, palatal, and velar plosives in three Australian languages. In addition, F2 variance at the vowel-consonant boundary, and, by extension, consonantal coarticulatory sensitivity, was measured. The locus equation slopes revealed that there were place-dependent differences in the magnitude of vowel-to-consonant coarticulation. As in previous studies, the non-coronal (bilabial and velar) consonants tended to be associated with the highest slopes, palatal consonants tended to be associated with the lowest slopes, and alveolar and retroflex slopes tended to be low to intermediate. Similarly, F2 variance measurements indicated that non-coronals displayed greater coarticulatory sensitivity to adjacent vowels than did coronals. Thus, both the magnitude of vowel-to-consonant coarticulation and the magnitude of consonantal coarticulatory sensitivity were seen to vary inversely with the magnitude of consonantal articulatory constraint. The findings indicated that, unlike results reported previously for European languages such as English, anticipatory vowel-to-consonant coarticulation tends to exceed carryover coarticulation in these Australian languages. Accordingly, on the F2 variance measure, consonants tended to be more sensitive to the coarticulatory effects of the following vowel. Prosodic prominence of vowels was a less significant factor in general, although certain language-specific patterns were observed
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ItemLeaders and Followers: Uptalk and speaker role in map tasks in New Zealand English and Australian English(Victoria University of Wellington, 2016-12-30)Recent work (Warren & Fletcher 2016) has considered how the shapes of uptalk rises differ from those of question rises in two antipodean varieties of English, New Zealand English (NZE) and Australian English (AusE). Both varieties appear to show some phonetic distinctions between uptalk and question rises, and while the details of the distinctions differ between the varieties, the net result is a more dynamic and dramatic rise in uptalk utterances. Other studies (e.g. Fletcher & Loakes 2010; Warren 2014) have shown that these distinctions are perceptually relevant and can be utilised in forced-choice tasks. In the current paper, the shapes of uptalk and question rises are examined in the speech of participants who each take on two different discourse roles – as Leaders or as Followers in map task interactions. The results are compatible with the different pragmatic goals of speakers in the two roles, with a reduction in the contrast between uptalk and question rises when the participant, as Follower, is largely reacting to the instructions given by the Leader, i.e. is responding in a context where common ground has been established.
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ItemThe acoustic characteristics of diphthongs in Indian English(Wiley, 2010-01-01)This paper presents the results of an acoustic analysis of English diphthongs produced by three L1 speakers of Hindi and four L1 speakers of Punjabi. Formant trajectories of rising and falling diphthongs (i.e., vowels where there is a clear rising or falling trajectory through the F1/F2 vowel space) were analysed in a corpus of citation-form words. In line with previous research, the diphthong inventory included six different diphthongs and a long monophthongal vowel [OI] in place of/partial derivative U/in GOAT; however, none of the speakers produced a full set of diphthong vowels. In addition, the/eI/diphthong, as in FACE, and the/U partial derivative/diphthong, as in TOUR, had both monophthongal and diphthongal realizations depending on the speaker. Overall, there was a great deal of variation in diphthong realization across the corpus but L1 appeared to be a relevant factor. Punjabi speakers showed a wider range of phonetic realizations for some of the vowels, and were more likely to produce long monophthongs rather than diphthongs. The results also highlight differences in the phonetic characteristics of several diphthongs between the speakers of two language backgrounds. The results of this study therefore contribute to the debate on the phonemic representation of IE vowels by taking into account different L1 influence (i.e., Hindi or Punjabi).