LOT summer school

Ultrasound, phonetics, phonology: Articulation for Beginners!

James M Scobbie CASL Research Centre

With special thanks to collaborators Jane Stuart-Smith & Eleanor Lawson Joanne Cleland & Zoe Roxburgh Natasha Zharkova, Laura Black, Steve Cowen Reenu Punnoose, Koen Sebreghts Sonja Schaeffler & Ineke Mennen Conny Heyde Alan Wrench (aka Articulate Instruments Ltd) for AAA software and UTI hardware Various funding – thank you to ESRC, EPSRC, QMU June 2013

• • • • – – Scottish English Derhoticisation among WC speakers Rhotic tongue shape Is it time for some nitty gritty stuff?

– Scottish English again Fronted /u/ – Extensions, if time Northern Irish /u/ and diphthongs Sociophonetics / Lg var & change

MRI – [o]

MRI – [i]

MRI – [y]

SSE /o/

What about real vowels?

• Example of a UTI vowel space, un-rotated

Front!

UTI single speaker for comparison

• Compare Daniel Jones (1917) – “frontness” in F2 & “frontness” in mm

Nature

• Whole tongue shape?

• Constriction degree / cross-sectional area / tube diameter?

• High point of the tongue surface? What about articulation?

• Vowels – /u/ in relation to /i/ in terms of “frontness” – /u/’s similarity to /i/ in tongue shape • Easy questions are still worth asking!

Some examples of something easy

• A socially-stratified corpus (ECB08) was collected to examine social variation in post vocalic /r/ articulation WC vs. MC teenagers • For context, each speaker produced just one (real word) token of each vowel phoneme • Labial consonants avoid lingual coarticulation • 9 monophthongal vowel phonemes • 3 diphthongs /ai/, /au/, /oi/ were not elicited • Single word citation forms, no carrier phrase • One time point was analysed – artic “target” Analysing minimal data sets

• Video UTI, so only ~30fps • Averaging acoustics is also hard – Male and female speakers – Adolescent speakers of variable vocal tract length • No opportunity for complex normalisation What can we get out of this?

•

WC n=8 , MC n=7 … 1 token each

hope Front!

beam fame hem hip boom map hum awe

How front is Scottish /u/?

• Formants are vocal tract resonances • A standard approach for 60 years has been to measure F1 & F2 – Low F1 = “height” & High F2 = “frontness” – We will come back to these metaphors later • Nothing is as simple as this metaphor implies, when you get down to detail – Higher formants are also important – Other factors affect these formants • But they are easy to measure, and plot well… Formants and frontness

• Hawkins and Midgely, cf Wells, Deterding

Front!

SSBE for comparison

• Calculate the F2 distance (Bark) from /i/, the vowel with the highest F2 – To /o/, /u/ and /e/ for each speaker – Repeat for a normalised set by treating the /i/-/o/ distance as 100% (corner vowel to corner vowel), which will make comparison to articulation easier • Calculate the distance (Bark) from /i/ – To /u/ and /e/ (and /o/) for each speaker – It was hard to measure F1 for /a/, so no normalisation Acoustic analysis

• /u/ is acoustically “non-back” • Relative to each speaker’s /i/ (& /o/), /u/ is

Front!

– Mid F2 (Hz) – Mid-high F2 (Bark) – 61% front (from /o/) e u o 0 -500

F2 relative to /i/ (Hz)

-1000 -1500 • /e/ has high F2 – 94% front • 2 speakers have /u/ < 50% front (just) Acoustic analysis -2000

• /u/ and /e/ are significantly “non-high” – /u/ not significantly different to /e/ or /o/ in F1 – In 5/14 speakers, /u/ had a higher rel F1 than /e/ – Hz / Bark are almost identical at these frequencies Acoustic analysis

• /u/ has a raised F2 – 2.6 Bark lower than /i/ – 4.1 Bark higher than /o/ • /u/ has a raised F1 – 0.6 Bark higher than /i/ – Non-distinct from the raised F1 of /e/, 0.4 Bark /u/ acoustic summary

• We only have mid-sagittal tongue curves – Not passive articulators (vocal tract tube) – Not all the tongue surface – Not all the internal tongue tissue – Not lips (well, not for this data set) – One token per speaker (for this data set) • But unlike EMA – We are not limited to 3 or 4 anterior points • And unlike MRI – UTI is cheap, non-invasive, portable and quick – We can collect & trace 12 tokens of 5V in half a day With UTI…

• UTI consistently shows Scottish / u / is lower and centralised/fronted compared to other vowels Vowel space (typical WC)

Front!

Vowel space (typical MC)

Front!

• What’s “horizontal” about a curving vocal tract?

• What’s the orientation of the probe to the head?

• Images can be rotated by you, looking, for qualitative understanding, if there is a fixed aspect ratio on x/y axes • Images can be rotated for quantitative analysis of “horizontal” and “vertical” by the analyst • Occlusal plane is replicable and standard and provides a reasonable horizontal for the anterior portion of the vocal tract High point of tongue

• ECB08 didn’t collect occlusal biteplanes… • Different shape hard palates don’t help • Two approaches to estimating “horizontal” rather than adopting the basic axes of the probe • common /o i/ tangent • Assumed occlusal ECB08 Soc-Lx sample

• /u/ is fronter in articulatory space than acoustics 91%, 2mm 74%, 6mm p<0.005

94% 61% i-o 90.0%, 2mm 99.6%, <1mm

Front!

occlusal • /u/ is either more front than central, or fully front Articulatory analysis

• /u/ is lower in articulatory space than acoustics • /u/ is not high and may be open-mid • It is lower than /e/ on either rotation of the space • /o/ is back… it’s not “lower” Articulatory analysis

• Analysis of even single tokens with only linear normalisation on an estimated bite plane (or /i/ /o/ mean) is at least as valid as acoustic analysis using normalised F2 (F2=frontness) – In terms of variation and statistical difference • Findings – /u/ is fronted & /o/ is the peripheral corner vowel – KIT vowel is lower in WC system – /u/ is much more radically lowered than expected • Need to improve quantification / averaging / axes for measurement space SSE summary and conclusions

• QMU Undergraduate project 2012-13 (Laura Black) looking at Northern Irish English (NIE) – /i e u ɔ/ & /au ai oi/ – n=12 – Mix of real & pseudo words, randomised in 3 blocks – All open syllables with onset /h/, /m/ or /b/ – 3 speakers – About 1 week of basic analysis from a standing start, followed by refinement (and checking) • Northern Irish-accented English .. Infamous for “confusing” and variable vowels …!

Typical undergrad student project

• What are monophthongs?

– /i/, /u/, /e/, /ɔ/?

– Traditional diphthongs are /ai/, /au/, /oi/ • How front is /u/?

• What singletons are the best phonological candidates for the offglides in the diphthongs?

• AAA demo NIE

NIE1 monophthongs

NIE1 diphthongs

NIE2 monophthongs

NIE2 diphthongs

NIE3 monophthongs

NIE3 diphthongs

• /u/ ends higher & fronter (almost = /i/) than SSE • More diphthongal than NIE /i/ or even NIE /e/ • Rounded

u i e

N. Irish /u/

But /u/ is a phonetic diphthong…

• /u/ is higher and fronter than ECB08 • Still ok for SSE • Still not as high as NIE Single speaker (SSE) Neutral space

• 28 (of 30) TD children (group 1) incl singletons: – Minimal vowels set (poop, babe, peep, pope etc) – DEAP (50w pL subtest and 12w screen) – Coarticulatory VCV materials (asa, isi etc) – Some coda /r/ words (hut, hurt, heart) • Other tasks were part of an experiment to test the “copyability” of US images on screen in – Group 1 vs. Group 3, raw vs. ULTRAX enhanced with presentation by machine and limited interaction – Group 2a vs. Group 2b raw vs. zero (acoustic only) with maximised interaction ULTRAX child corpus

ULTRAX (g1, 2012) TD 11, 23, 24, 31

• Are the ULTRAX kids like the ECB08 corpus teenagers?

• Yes  More /u/ (i-o plane)

• Are ULTRAX group 2 like ULTRAX group 1?

• Yes, pretty much, so far (n=15) More /u/ (i-o plane)

• Rotation of ECB08 20° (assumed biteplane) – Similar results obtained using /i/-/o/ common tangent, which is about 45 ° different in orientation – Axes provided by the probe are intermediate – Close “high points” on these curves are tolerant of axes shift

/o/ /e/ /u/ /i/

Quantifying /u/ frontness

H -20