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Ultrasound-based tongue root imaging and measurement
James M Scobbie
QMUWith thanks to collaborators
Jane Stuart-Smith, Marianne Pouplier, Alan Wrench,
Eleanor Lawson, Olga Gordeeva
2Introduction
• Pros and cons of Ultrasound Tongue Imaging
• EPG/UTI experiment on English /l/– Alveolar contact or vocalisation– Light and dark allophones of /l/
• The ECB08 UTI corpus– Scottish derhoticisation and articulation of /r/– Vowel system– A handful of /l/ again…
• Demo of AAA software
4Pros and cons of UTI
• Pro– Tongue root to blade in one image– Instant, real-time, easy, safe, cheap– Qualitative and quantitative analysis– Can be combined with other techniques
• Con– Image quality is variable– Hardly any constriction or info on passive articulator– Frame rate of video output is only ~30Hz (~33ms)– Synchronisation with acoustics is problematic– Quantitative analysis is time-consuming and as yet
poorly developed… what to measure?
6English /l/
• /l/ is lighter in onset, darker in coda
• Many accents have “vocalisation” in coda
• EPG + UTI study of 10 speakers– UTI image quality uniformly awful – EPG results very interesting – Context was /i/+/l/ (+ {/b/, /h/, /l/}) +/i/
• Pee leewards, peel beavers, peel heaps of, etc.
• EPG results– Reduction or loss of alveolar contact in codas– Reduced palatal contact (compared to /i/) due to /l/
7Example onset
• Alveolar contact in orange, palatal in green• S2 typical in losing palatal contact in onset
(can we pee leewardin a gentlebreeze)
8
• No alveolar contact, more palatal contact
(can we peel BBC advertisingfrom the shop window)
Example coda_b retraction
9EPG results: loss of palatal contact
• E + S1: light onset and dark coda in palatality
• Scots S2,3,4 show darker (less [i]-like) onset
• Question 1: what about intergestural timing?
• Question 2: what about the pharyngeal aspect of darkness rather than loss of palatality?
0%
20%
40%
60%
80%
100%
S1 S2 S3 S4Speaker
Co
nta
ct i
-Zo
ne
Onset gemambi Coda_hCoda_b
0%
20%
40%
60%
80%
100%
E1 E2 E3 E4 E5Speaker
Co
nta
ct
i-Z
on
e
Onset gemambi Coda_hCoda_b
10EPG results: timing
• Relatively simultaneous alveolar contact and loss of palatality in onset
• Alveolar contact is delayed in coda (or missing) and loss of palatality occurs earlier
-60
-40
-20
0
20
40
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80
100
120
onset gem ambi coda_h coda_b
context
La
g (
ms)
S
E
12UTI: Scottish pharyngealisation?
• Measurement of Tongue root retraction in [i] and in [l] for a single sample speaker S2– Coping with terrible quality UTI
• Find frames of maximum advancement and maximum retraction of root just above hyoid shadow)– Typical problems in measuring images
14Example onset
• This is only a bit better than guessing, but impression is of slight pharyngealisation
15Results (S2, n = 18)
• Tongue root retracts earlier in coda_b (p<0.01)– Max advancement appears to be near end of [i] vowel in
onset condition and mid-way through [i] in coda_b condition– Max retraction apparently at end of [l] in onset condition and
towards the end of [b] in coda_b condition
• [i] is less advanced in coda_b than onset (p<0.005)– There is a n.s. trend for greater pharyngealisation in coda [l]
retraction duration
0
50
100
150
200
onset coda_b
ms
retraction distance
3
3.5
4
4.5
5
i lm
m
onset
coda_b
16Conclusions
• Darkness as measured by decrease in palatality in /i/ context shows onset/coda differences for only some speakers– Probably dialectal: Scots /l/ is less [i]-like in onset
• “All” speakers show a strong timing difference– Front and back gestures dissociate in coda so that
posterior gesture is earlier and alveolar (if present at all in coda) is later (“gestural dissociation”)
• Qualitative (and quantitative) analysis of UTI data probably shows greater pharyngealisation for all speakers’ coda than onset.
17ECB08
• Ultrasound/acoustic corpus – 15 teenagers (12-14) in friendship pairs (+4 11yrs)– Wordlist and some spontaneous discourse– Half from a WC and half from a MC school– Main purpose to test effect of use of UTI on
vernacular speech variables
• Secondary purpose– Derhoticisation of coda /r/ - pharyngealisation?– Vowel space
• But sadly not much room for– Vocalisation of coda /l/ - pharyngealisation?
18Derhoticised coda /r/
Hiya my name's Kaj McInally
My company's FinesseDecor (Scotland) Ltd
I'm not a manager. I'm a painter and decorator
to trade, first and foremost
who just so happened to start work for myself, and then
we’ve been that... kinda... successful that we've had to take on people
19Losing /r/ in Scotland
• Since the 1970s coda /r/-“loss” has been reported in working class speech– Not the RP-like middle-class non-rhoticity
• Stuart-Smith (2003) in a Glasgow corpus including 14-15 year old children showed that WC girls have no overtly rhotic consonant for coda /r/ in approximately 90% of cases, boys in about 80%– Middle class children and older adults are rhotic, so the
stratified derhoticisation is indicative of change in progress.– /r/ seems to be turning into a vowel right now– Strong impression of pharyngealisation offglide on vowels
with monophthongal pharyngealisation on low back ones
20
rain, with an anterior approximant, usually described as being “retroflex” (note low F3)
ferry, with a tap (an approximant is more common)
F3F2
Typically rhotic tokens of Scottish /r/
21Word-final derhoticisation in ECB08
Rhotic ear (above) car (below)
F3F2
F3F2
F3F2
F3F2
Derhoticised ear (above) car (below)
22Rhotic (MC) speakers
• Lexical sets BIRD WORD HERD merged (8/11)– Earth, verb, berth, (err) = third, word, surf, birth, fur– Could be a rhotic vowel /ɚ/
• No /a/ split (Pam/palm are homophones)
• /ʉ/ is central and not very high
iɹ ʉɹ oɹ
eɹ ɚ ɔɹ
ɑɹ
i ʉ o
e ı ɔ
ɛ a ʌ
28
iə ʉə oʌ
eə ɔˤ
ɛˤ ɑː (ʕ)
• More vowels (and environments) with weak /r/– No merger of /ɛr/ and /ʌr/ (8/8)– /a/ split (hat/heart) [a] vs. [ɑ] for the most derhotic– /ʌr/ is short without compensatory lengthening– High vowels create diphthongs– Pre-pausal /r/ tends to devoice
• Potential /ʌ/ merger (hut/hurt, bud/bird)
i ʉ o
e ı ɔ
ɛ a ʌ
Derhoticising (WC) speakers
29
Pre-pausal /r/ may have late (covert?) tip
car
• Low vowels sound derhoticised, acoustically lack F2/F3 approximation, and are near-monophthongs.
• Articulatorily a clear rhotic gesture was retained
31
• What about /l/?– If dark, is it pharyngealised?– If vocalised, is it a pharyngeal?– How are derhoticised /r/ & vocalised /l/ kept apart?– Hip hum hut– Fur/fir hurt– Pill film– Mull bulb cult
• Clear difference between /r/ and /l/ in open and closed syllables
/l/ in a derhoticising (WC) speaker
32UTI of laterals
– Red = // mull (cons) & bulb (vocalised)– Blue = /ı/ film (cons) & pill (vocalised)
• Pharyngealisation vs. velarisation?
33UTI of laterals
– Red = cult (cons /lt/)– Green = hurt (cons /t/)
• /l/ pharyngealised + velarised?
• Pharyngealised postalveolar /r/ with saddle
35Conclusions
• Onset/coda differences in /l/ in a high vowel context are well-known to involve loss of palatality and a greater pharyngeal constriction (Sproat and Fujimura 1993), plus subtle loss of alveolar contact (eg Giles & Moll)
• Scottish speakers who have no onset/coda difference in palatality do show increased pharyngealisation in coda (and may show very strong vocalisation, not gestural undershoot)
• Vocalised /l/ may be velarised while pharyngealisation occurs for consonantal /l/
36Conclusions
• Derhoticisation often sounds like pharyngealisation
• But in prepausal and other masking contexts there can be delayed covert post-alveolar constriction, due to “gestural dissociation”
• WC /r/ seems to be changing from consonant into vowel, with some increase in vowel space
• Meanwhile, MC rhotic speakers merge vowels• WC /l/ and /r/ seem to be keeping distinct
– Is the pharyngealised /l/ also velarised?– Is the difference purely anterior?
37AAA demo
• Let’s look at pharyngealisation in a derhoticising speaker – Hut vs. hurt– Bud vs. bird– Far vs. fir
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