Category Archives: Research

These posts are dedicated to my research.

The articulation of /ɹ/ in New Zealand English

Matthias Heyne, Xuan Wang, myself (Donald Derrick), Kieran Dorreen, and Kevin Watson have recently had an article documenting the articulation of  /ɹ/ in New Zealand English.

This work is therefore in part a follow-up to some of my co-authored research into biomechanical modelling of English  /ɹ/ variants, indicating that vocalic context influences variation through muscle stress, strain, and displacement.  It is, by these three measures, “easier” to move from an /i/ to a tip-down /ɹ/ , but from /a/ to a tip-up /ɹ/.

In this study, for speakers who vary at all (some only do tip-up or tip-down), they are most likely to produce tip-up /ɹ/ in these conditions:

back vowel > low central vowel > high front vowel

initial /ɹ/ > intervocalic /ɹ/ > following a coronal (“dr”) > following a velar (“cr”)

The results show that allophonic variation of NZE /ɹ/ is similar to that in American English, indicating that the variation is caused by similar constraints.  The results support theories of locally optimized modular speech motor control, and a mechanical model of rhotic variation.

The abstract is repeated below, with links to articles contained within:

This paper investigates the articulation of approximant /ɹ/ in New Zealand English (NZE), and tests whether the patterns documented for rhotic varieties of English hold in a non- rhotic dialect. Midsagittal ultrasound data for 62 speakers producing 13 tokens of /ɹ/ in various phonetic environments were categorized according to the taxonomy by Delattre & Freeman (1968), and semi-automatically traced and quantified using the AAA software (Articulate Instruments Ltd. 2012) and a Modified Curvature Index (MCI; Dawson, Tiede & Whalen 2016). Twenty-five NZE speakers produced tip-down /ɹ/ exclusively, 12 tip-up /ɹ/ exclusively, and 25 produced both, partially depending on context. Those speakers who produced both variants used the most tip-down /ɹ/ in front vowel contexts, the most tip- up /ɹ/ in back vowel contexts, and varying rates in low central vowel contexts. The NZE speakers produced tip-up /ɹ/ most often in word-initial position, followed by intervocalic, then coronal, and least often in velar contexts. The results indicate that the allophonic variation patterns of /ɹ/ in NZE are similar to those of American English (Mielke, Baker & Archangeli 2010, 2016). We show that MCI values can be used to facilitate /ɹ/ gesture classification; linear mixed-effects models fit on the MCI values of manually categorized tongue contours show significant differences between all but two of Delattre & Freeman’s (1968) tongue types. Overall, the results support theories of modular speech motor control with articulation strategies evolving from local rather than global optimization processes, and a mechanical model of rhotic variation (see Stavness et al. 2012).

Trip to Taiwan: Talks and conference

I spent October 14 to October 23, 2017 in Taiwan, giving many talks.  My first was a talk at National Taiwan university on Monday the 16th.  There I spoke about commercializing research.

On Wednesday the 18th, I went to Academia Sinica and the Institute of Linguistics and spoke on aero-tactile integration in speech perception.

Lastly, on the weekend of the 21-22nd, I spoke at workshop at National Tsing Hua University (my hosts) on ultrasound and EMA research.

If you want copies of the talks, send me an email to my work.  Apologies for the hassle: They are all too large to post to this website.

Ultrasound/EMA guide

This is a guide to the use of ultrasound and EMA in combination.  It is a bit out of date, and probably needs a day or two of work to make fully correct, but it describes the techniques I use with 3 researchers.  Of course I wrote this years ago, and now I can run an Ultrasound/EMA experiment by myself if I need to.