1. PHREND at UCSC Sepember 24, 2016 Sarah Bakst, UC Berkeley
Modeling the effect of palate shape on the articulation and acoustics of American English /r/
PHREND at UCSC
Sepember 24, 2016
Sarah Bakst, UC Berkeley

2. Overview What is the role of individual anatomy in speech production?
Here: domedness of palate
Mapping between articulation and acoustics
Test case: American English /r/
This work models an answer to the question, “what is the role of individual anatomy in speech production?”

3. Role of palate shape
Brunner et al. (2009): flatness correlated with reduced articulatory variability but not acoustic variability for front vowels
Bakst (2016): extension to /r/

4. Articulatory variability
Articulatory and acoustic variability compared by palate shape in /r/ production
Articulatory variability
(z-scored)
pdf(‘rtic.pdf’, height = 6, width = 10)
plot(dd$rscale~dd$alpha, main = 'Variability in production correlated with palate shape for /r/ ', ylim = c(-2,2), xlab = 'Flatness', ylab = 'Variability', type = 'n')
points(dd$rscale~dd$alpha, pch = 15)
abline(3.552,-1.728)
dev.off()
plot(dd$f3scale~dd$alpha, col = 'red')
abline(1.4910, , col = 'red', lty = 2)
Acoustic variability
(z-scored F3 s.d.)
1.8
2.0
2.2
2.4
2.6
Palate flatness

5. Quantal mapping arbitrary constriction along vocal tract
(figure from Stevens & Keyser 2010)

6. Domedness as a factor
Palate shape affects mapping between articulation and acoustics (Stevens 1972)
Differences in width of zone II
Differences in location and frequency of discontinuities

7. Motivation
Observation: flat palates -> reduced articulatory variability
What is the nature of this relationship between palate shape and articulatory/acoustic variability?
Is the articulatory-acoustic mapping actually different for different palate shapes?
Or is there just less room to move?
Test with F3 in /r/ as acoustic parameter

8. Hypothesis Main hypothesis: Less linear mapping =
Wider ‘zone II’ for flatter palates, hence constrained articulatory variability
Less linear mapping =
larger areas of local acoustic stability (domed)
more discontinuities in F3 values for domed palates
More linear mapping =
more acoustic flexibility (flat)
Greater range in F3 value for flatter palates

9. Modeling in Maeda Maeda synthesizer Default:
one relatively domed-average palate
four articulatory principal components based on real human:
jaw/tube
dorsum position
dorsum shape
apex position

10. Maeda revised New parameter: apex orientation ant post ant bunched /r/
retroflex /r/
bunched /r/

11. Tongue tip
lips
glottis

12. Palates Maeda comes with one default palate
I additionally created a flat palate and a super-domed palate

13. New palates

14. Methods
Settings for each parameter (below: dorsum shape) on a scale from -4 to 4
Component multiplied by setting

15. Method Four manipulated parameters:
Dorsum position (anteriority)
Dorsum shape (bunchiness)
Apex shape (tip-up/-down)
Lip protrusion
Python script looped over values for each articulatory parameter
Model plays through vocal tract
Formant tracking in ifc formant
Rejection of bad tokens: low rms amplitude

16. Area function Area taken at 32 places along vocal tract
Synthesizer uses special formula taking into account domedness of palate:
A (x) = αx^β
α is a metric of domedness; x = width in sagittal plane
α empirically-derived

17. Results: Zone width

22. Correlations with F3 Flat Default Domed Dorsum position -0.52 -0.64
-0.63
Dorsum shape
-0.47
-0.32
-0.19
Lip protrusion
-0.05
-0.14
-0.24
Tip curl
-0.09

23. Correlations with F3 Flat Default Domed Dorsum position -0.52 -0.64
-0.63
Dorsum shape
-0.47
-0.32
-0.19
Lip protrusion
-0.05
-0.14
-0.24
Tip curl
-0.09

24. Correlations with F3 Flat Default Domed Dorsum position -0.52 -0.64
-0.63
Dorsum shape
-0.47
-0.32
-0.19
Lip protrusion
-0.05
-0.14
-0.24
Tip curl
-0.09

25. Correlations with F3 Flat Default Domed Dorsum position -0.52 -0.64
-0.63
Dorsum shape
-0.47
-0.32
-0.19
Lip protrusion
-0.05
-0.14
-0.24
Tip curl
-0.09

26. Correlations with F3 Flat Default Domed Dorsum position -0.52 -0.64
-0.63
Dorsum shape
-0.47
-0.32
-0.19
Lip protrusion
-0.05
-0.14
-0.24
Tip curl
-0.09

27. Lowest F3 configurations

28. Discussion
Smallest “zone I” for flattest palate–theoretically a wider range of attainable acoustic output
Effect of each articulator on F3 actually varies by palate shape
Supports result linking reduced articulatory variability with flatter palate shape

29. Conclusions
Palate shape does seem to have an influence over the articulatory-acoustic mapping
Implications for sound change?
Next step:
add sublingual cavity
expectations: sublingual cavity significant lowering effect (usually on F3)
better articulatory predictions

30. Acknowledgements Ronald Sprouse Keith Johnson Susan Lin John Houde
Rich Ivry
Members of the UC Berkeley Phon Lab

31. Selected references
B. S. Atal, J. J. Chang, M. V. Matthews, and J. W. Tukey, “Inver- sion of articulatory-to-acoustic transformation in the vocal tract by a computer-sorting technique,” Journal of the Acoustical Society of America, vol. 63, no. 5, pp. 1535–1555, 1978.
Bakst, S. (2016). The role of palate shape in individual articulatory and acoustic variability. Laboratory Phonology 15.
Brunner, J., S. Fuchs, and P. Perrier (2009). On the relationship between palate shape and articulatory behavior. Journal of the Acoustical Society of America 125(6), 3936–3949.
Carre, R. and M. Mrayati (1988). Articulatory-acoustic-phonetic relations and modeling, regions, and modes. In A. Marchal and W. Hardcastle (Eds.), Speech production and speech modeling, NATO ASI Series. Dordrecht: Kluwer Academic Publishers.
Espy-Wilson, C. Y., S. Boyce, M. Jackson, S. Narayanan, and A. Alwan (2000). Acoustic modeling of American English /r/. Journal of the Acoustical Society of America 108(1), 343–356.
J. Mielke, A. Baker, and D. Archangeli, “Variability and homo- geneity in American English /r/ allophony and /s/ retraction,” Lab- oratory Phonology, vol. 10, pp. 699–729, 2010.
Mrayati, M., R. Carre, and B. Guerin (1988). Distinctive regions and modes: a new theory of speech production. Speech Communication 7, 257–286.
Stevens, K. N. and S. E. Blumstein (1975). Quantal aspects of consonant production and perception: a study of retroflex stop consonants. Journal of Phonetics 3, 215–233.
Stevens, K. N. and S. J. Keyser (2010). Quantal theory, enhancement and overlap. Journal of Phonetics 38,
A.Watanabe,“Formantestimationmethodusinginversefiltercon- trol,” IEEE Transactions on Speech and Audio Processing, vol. 9, no. 4, pp. 317–26, 2001.