@misc{WilliamsEscuderoGafos2018,
  author    = {Williams, Daniel and Escudero, Paola and Gafos, Adamantios I.},
  title     = {Perceptual sensitivity to spectral change in Australian English close front vowels},
  series = {19 th annual conference of the international speech communicaton association (INTERSPEECH 2018), VOLS 1-6: Speech research for emerging marjets in multilingual societies},
  journal   = {19 th annual conference of the international speech communicaton association (INTERSPEECH 2018), VOLS 1-6: Speech research for emerging marjets in multilingual societies},
  publisher = {ISCA-International Speech Communication Association},
  address   = {Baixas},
  isbn      = {978-1-5108-7221-9},
  issn      = {2308-457X},
  doi       = {10.21437/Interspeech.2018-2505},
  pages     = {1442 -- 1446},
  year      = {2018},
  abstract  = {Speech scientists have long noted that the qualities of naturally-produced vowels do not remain constant over their durations regardless of being nominally "monophthongs" or "diphthongs". Recent acoustic corpora show that there are consistent patterns of first (F1) and second (F2) formant frequency change across different vowel categories. The three Australian English (AusE) close front vowels /i:, 1, i/ provide a striking example: while their midpoint or mean F1 and F2 frequencies are virtually identical, their spectral change patterns distinctly differ. The results indicate that, despite the distinct patterns of spectral change of AusE /i:, i, la/ in production, its perceptual relevance is not uniform, but rather vowel-category dependent.},
  language  = {en}
}
@article{MokariGafosWilliams2021,
  author    = {Mokari, Payam Ghaffarvand and Gafos, Adamantios I. and Williams, Daniel},
  title     = {Perceptuomotor compatibility effects in vowels},
  series = {JASA Express Letters},
  volume    = {1},
  journal   = {JASA Express Letters},
  number    = {1},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {2691-1191},
  doi       = {10.1121/10.0003039},
  pages     = {8},
  year      = {2021},
  abstract  = {In a cue-distractor task, speakers' response times (RTs) were found to speed up when they perceived a distractor syllable whose vowel was identical to the vowel in the syllable they were preparing to utter. At a more fine-grained level, subphonemic congruency between response and distractor-defined by higher number of shared phonological features or higher acoustic proximity-was also found to be predictive of RT modulations. Furthermore, the findings indicate that perception of vowel stimuli embedded in syllables gives rise to robust and more consistent perceptuomotor compatibility effects (compared to isolated vowels) across different response-distractor vowel pairs.},
  language  = {en}
}
@article{MayrMorrisMennenetal.2017,
  author    = {Mayr, Robert and Morris, Jonathan and Mennen, Ineke and Williams, Daniel},
  title     = {Disentangling the effects of long-term language contact and individual bilingualism: The case of monophthongs in Welsh and English},
  series = {International journal of bilingualism : cross-disciplinary, cross-linguistic studies of language behavior},
  volume    = {21},
  journal   = {International journal of bilingualism : cross-disciplinary, cross-linguistic studies of language behavior},
  publisher = {Sage Publ.},
  address   = {London},
  issn      = {1367-0069},
  doi       = {10.1177/1367006915614921},
  pages     = {245 -- 267},
  year      = {2017},
  abstract  = {Aims and objectives: This study investigates the effects of individual bilingualism and long-term language contact on monophthongal vowel productions in English and Welsh. Design: To this end, we recorded the Welsh and English vowel productions of two sets of Welsh-English bilinguals differing in home language use, as well as the English vowel productions of English monolinguals. Data and analysis: The data were analysed acoustically, with a focus on spectral and temporal properties. Comparisons were then made within each language and cross-linguistically. Findings: The results of a cross-linguistic acoustic comparison revealed a high degree of convergence in the monophthong systems of Welsh and English, but also some language-specific categories. Interestingly, at the individual level we found no effect of linguistic experience on vowel production: the two sets of bilinguals and the English monolinguals did not differ in their realisation of English vowels, and the two sets of bilinguals did not differ in their realisation of Welsh vowels. Implications: The findings demonstrate pervasive phonetic convergence in a language contact situation with a historical substrate. They also indicate that a homogeneous peer group with shared values can override the effects of individual linguistic experience.},
  language  = {en}
}
@article{GhaffarvandMokariGafosWilliams2020,
  author    = {Ghaffarvand-Mokari, Payam and Gafos, Adamantios I. and Williams, Daniel},
  title     = {Perceptuomotor compatibility effects in vowels},
  series = {Attention, perception, \& psychophysics},
  volume    = {82},
  journal   = {Attention, perception, \& psychophysics},
  number    = {5},
  publisher = {Springer},
  address   = {New York},
  issn      = {1943-3921},
  doi       = {10.3758/s13414-020-02014-1},
  pages     = {2751 -- 2764},
  year      = {2020},
  abstract  = {Perceptuomotor compatibility between phonemically identical spoken and perceived syllables has been found to speed up response times (RTs) in speech production tasks. However, research on compatibility effects between perceived and produced stimuli at the subphonemic level is limited. Using a cue-distractor task, we investigated the effects of phonemic and subphonemic congruency in pairs of vowels. On each trial, a visual cue prompted individuals to produce a response vowel, and after the visual cue appeared a distractor vowel was auditorily presented while speakers were planning to produce the response vowel. The results revealed effects on RTs due to phonemic congruency (same vs. different vowels) between the response and distractor vowels, which resemble effects previously seen for consonants. Beyond phonemic congruency, we assessed how RTs are modulated as a function of the degree of subphonemic similarity between the response and distractor vowels. Higher similarity between the response and distractor in terms of phonological distance-defined by number of mismatching phonological features-resulted in faster RTs. However, the exact patterns of RTs varied across response-distractor vowel pairs. We discuss how different assumptions about phonological feature representations may account for the different patterns observed in RTs across response-distractor pairs. Our findings on the effects of perceived stimuli on produced speech at a more detailed level of representation than phonemic identity necessitate a more direct and specific formulation of the perception-production link. Additionally, these results extend previously reported perceptuomotor interactions mainly involving consonants to vowels.},
  language  = {en}
}
@article{ChladkovaHamannWilliamsetal.2017,
  author    = {Chladkova, Katerina and Hamann, Silke and Williams, Daniel and Hellmuth, Sam},
  title     = {F2 slope as a Perceptual Cue for the Front-Back Contrast in Standard Southern British English},
  series = {Language and speech},
  volume    = {60},
  journal   = {Language and speech},
  publisher = {Sage Publ.},
  address   = {London},
  issn      = {0023-8309},
  doi       = {10.1177/0023830916650991},
  pages     = {377 -- 398},
  year      = {2017},
  abstract  = {Acoustic studies of several languages indicate that second-formant (F2) slopes in high vowels have opposing directions (independent of consonantal context): front [i.]-like vowels are produced with a rising F2 slope, whereas back [u.]-like vowels are produced with a falling F2 slope. The present study first reports acoustic measurements that confirm this pattern for the English variety of Standard Southern British English (SSBE), where /u./ has shifted from the back to the front area of the vowel space and is now realized with higher midpoint F2 values than several decades ago. Subsequently, we test whether the direction of F2 slope also serves as a reliable cue to the /i.// u./ contrast in perception. The findings show that F2 slope direction is used as a cue (additional to midpoint formant values) to distinguish /i./ from /u./by both young and older Standard Southern British English listeners: an otherwise ambiguous token is identified as /i./if it has a rising F2 slope and as /u./if it has a falling F2 slope. Furthermore, our results indicate that listeners generalize their reliance on F2 slope to other contrasts, namely /epsilon/-/./and /ae/-/./, even though F2 slope is not employed to differentiate these vowels in production. This suggests that in Standard Southern British English, a rising F2 seems to be perceptually associated with an abstract feature such as [+ front], whereas a falling F2 with an abstract feature such as [-front].},
  language  = {en}
}