an mri-based cross-linguistic study of sibilant fricatives martine toda 1,2 & kiyoshi honda 1 1...
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An MRI-based cross-linguistic study of sibilant fricatives
Martine Toda 1,2 & Kiyoshi Honda 1
1 ATR, Human Information Science Laboratories, Japan.2 Laboratoire de Phonétique et Phonologie UMR 7018,
Université Paris III / CNRS, France.
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‘Sibilant fricatives’
• Fricatives produced with clenched teeth (or the upper teeth close to the lower lip) (Ladefoged and Maddieson, 1996)
• Acoustically characterized by a loud frication noise (Shadle, 1985)
• Distinguished each other by their noise spectrum (Harris, 1958)
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Sibilant fricatives in Toda (a Dravidian language spoken in India), Ladefoged and Maddieson (1996, p.160)
Sibilants: a consonantal subsystem
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Aims of the study
To examine• how sibilants are contrasted with each other in
articulation
and• how the articulatory space is delimited by
phonological features
Method
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Languages, sibilants and subjects
unvoiced sibilant
fricatives
3 sibilants system
/ , / / , / / , , /
type of contrast palatalizationplace of
articulationboth
language Japanese French English Chinese Swedish
number of subjects
97 5 4 1
12 5
2 sibilants systems
front
contrast of place of articulation
back
contrast of place of articulation
palatalized
contrast of palatalization
not palatalized
contrast of palatalization
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MRI data acquisition
• Sibilant fricatives– Sustained fricatives
– Supine position
• Teeth – tongue and lips kept tightly
close to teeth
directionscanned
arearesolution
slice thickness
and spacingTE TR
scan duration
sagittal128 mm 128 mm
45 mm
0.25 mm 0.25
mm1.5 mm 3.3 ms 10 ms 23 s
The Shimadzu-Marconi ECLIPSE 1.5T scanner at ATR’s Brain Activity Imaging Center
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Redeeming teethoriginal MRI data
sibilants
teeth
merging teeth and articulatory data
The three data sets are manually fitted in Intage rv (KGT Inc.); Estimated precision: 0.25 mm and 0.5
extracted teeth shape
upper teeth
lower teeth
}
extraction helped by rough hand tracing
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Articulatory measurements
place of articulation
mid-sagittal slice
tongue shape
palatalization index =front cavity area =
Results
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front cavity area (mm2)
pala
taliz
atio
n in
dex
(mm
)
ssj
s
s
ellipses for 2
s
Fr.
Fr.
En.
Ch.
Ch.
Sw.
J.
J.
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front cavity area (mm2)
pala
taliz
atio
n in
dex
(mm
)
ssj
s
s
ellipses for 2
sj and
Ch.
Ch.
Sw.
J.
J.
ISSP 2003 An MRI-based cross-linguistic study of sibilants
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front cavity area (mm2)
pala
taliz
atio
n in
dex
(mm
)
ssj
s
s
ellipses for 2
and
Fr.
Fr.
En.
Ch.
Ch.
Sw.
Discussion
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front cavity area (mm2)
pala
taliz
atio
n in
dex
(mm
)
ssj
s
s
ellipses for 2
Feature specification and articulatory space
s
sj
s
s
ISSP 2003 An MRI-based cross-linguistic study of sibilants
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front cavity area (mm2)
pala
taliz
atio
n in
dex
(mm
)
ssj
s
s
ellipses for 2
Redundant feature specification
s
sj
s
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front cavity area (mm2)
pala
taliz
atio
n in
dex
(mm
)
ssj
s
s
ellipses for 2
Inventory size and articulatory space
ss
Conclusion
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Summary
• /s/ front, /sj and / long constriction, / and / back and // shorter constriction than // in 3 sibilants languages
• Articulatory space split into smaller parts when a feature (dimension) is consistent;
• Articulation specified for all consistent features even when redundant;
• Size of articulatory space do not directly depend on inventory size
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Further challenges
• Refining articulatory measures– Measures of vocal tract shape => systematic
relationship with the acoustics
• Language-dependent articulatory space – why ?– Need to take into account a larger consonantal
subsystem ?
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Acknowledgement
• Thanks to:Chunyue Zhu
Alexis Michaud
Fredrik Bissmarck
• Work supported by the Telecommunications Advancement Organization of Japan