Presentation on theme: "James M Scobbie CASL Research Centre LOT summer school Ultrasound, phonetics, phonology: Articulation for Beginners! With special thanks to collaborators."— Presentation transcript:
James M Scobbie CASL Research Centre LOT summer school Ultrasound, phonetics, phonology: Articulation for Beginners! 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
Sociophonetics / Lg var & change 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
MRI – [o]
MRI – [i]
MRI – [y]
What about real vowels?
UTI single speaker for comparison Example of a UTI vowel space, un-rotated Front! Front?
What about articulation? Compare –“frontness” in F2 & “frontness” in mm –“height” in F1 & “height” in mm What are articulatory frontness and height? Whole tongue shape? Constriction degree / cross-sectional area / tube diameter? High point of the tongue surface? Daniel Jones (1917) Experimental phonetics and its utility to the linguist. Nature 100:
Some examples of something easy Vowels –/u/ in relation to /i/ in terms of “frontness” –/u/’s similarity to /i/ in tongue shape Easy questions are still worth asking!
Analysing minimal data sets 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”
What can we get out of this? 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
How front is Scottish /u/? hem beam fame hip map boom hum awe hope WC n=8, MC n=7… 1 token each Front!
Formants and frontness 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…
SSBE for comparison Hawkins and Midgely, cf Wells, Deterding Front!
Acoustic analysis 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 –Mid F2 (Hz) –Mid-high F2 (Bark) –61% front (from /o/) /e/ has high F2 –94% front 2 speakers have /u/ < 50% front (just) Front!
Acoustic analysis /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
/u/ acoustic summary /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
With UTI… 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
UTI consistently shows Scottish / u / is lower and centralised/fronted compared to other vowels Front! Vowel space (typical WC)
Front! Vowel space (typical MC)
High point of tongue 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
common /o i/ tangent Assumed occlusal 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 ECB08 Soc-Lx sample
Articulatory analysis /u/ is fronter in articulatory space than acoustics /u/ is either more front than central, or fully front 99.6%, <1mm 90.0%, 2mm 91%, 2mm 74%, 6mm 94% 61% p<0.005 i-o occlusal 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”
SSE summary and conclusions 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
Typical undergrad student project QMU Undergraduate project (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 …!
NIE 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
N. Irish /u/ /u/ ends higher & fronter (almost = /i/) than SSE More diphthongal than NIE /i/ or even NIE /e/ Rounded u i e
But /u/ is a phonetic diphthong…
Single speaker (SSE) Neutral space /u/ is higher and fronter than ECB08 Still ok for SSE Still not as high as NIE
ULTRAX child corpus 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 (g1, 2012) TD 11, 23, 24, 31
More /u/ (i-o plane) 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)
Quantifying /u/ frontness 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/ /i/ /e/ /u/ H -20