Dept. for Speech, Music and Hearing
Quarterly Progress and
Status Report
Coarticulation of stops with
vowels
Öhman, S.
journal:
volume:
number:
year:
pages:
STL-QPSR
4
2
1963
001-008
http://www.speech.kth.se/qpsr
I.
SPEECH PRODUCTION
COARTICULATION OF STOPS WITH VOWFLS
A.
X-ray d a t a
Observations on a s e r i e s of Danish s y l l a b l e s
/gi
7
ge 9
9
g?, gy, gb? @ 9 go, €33, ga/ by means of X-ray
moving p i c t u r e s i n d i c a t e t h s t t h e t o n g u e 9 s motion from t h e
" r e s t i n g p o s i t i o n " t o t h e g-closure
t i t y c f t h e f o l l o w i n g vowel
i s a f f e c t e d by t h e iden-
Those p a r t s of t h e tongue
which a r e n o t under t h o c o n t r o l of t h c s t o p ? r t i c u l = ~ t i o nbegin
t o assume a shape which approaches t h a t of t h e f o l l o w i n g vowel
a h e a d g a t t h e onset of t h e production of t h e s t o p .
R e c a c t l y , c e r t a i n a t t s m p t s have been made t o apply
a dynamic model of a r t i c u l a t i o n i n which t h e speech organs a r e
assumed t o be c o n t r o l l e d by a time d i s c r e t e sequence of n e u r a l
i n s t r u c t i o n s t h a t a r e simply r e l a t e d t o t h e i n v e n t o r y of a l l o phones of a language ( 2 ) ( 3 )
.
(4) ( 5 ) ( 6 ) ( 7 )
Certain aspects
of vowel r e d u c t i o n may be g i v e n a v e r y s z t i s f a c t o r y e x p l a n a t i o n
cn t h e b a s i s of t h i s assumption
(5).
It i s proposed h e r o t h a t
t h e phenomenon r e f e r r e d t o i n t h e f i r s t paragraph may be accounted f o r I n a s i m i l a r manner, v i e . , by assuming t h a t t h e
a r t i c u l a t o r y system r e c e i v e s a double i n s t r u c t i o n a t t h e beg i n n i n g of t h e CV s y l l a b l e .
Ona of t h e s e i n s t r u c t i o n s c a u s e s a
motion i n t h e d i r e c t i o n of t h e vowel and t h e o t h e r one t r i g g e r s
a c l o s u r e g e s t u r e , which seems t o involve l e s s of t h e a v a i l a b l e
musculatura.
The c l o s u r e g e s t u r e i s superimposed upon t h e
vowel mot i o n
T h i s i d e a i s i l l u s t r a t e d i n Fig. 1-1.
The mid-
s a g i t t a l c r o s s - s e c t i o n of t h e v o c a l t r a c t i s h e r e r e p r e s e n t e d
by a polygonal box with t h e " l i p s " t o t h e r i g h t and t h e " g l o t t i s "
t c the l e f t .
Boxes Nos. A l , A9, and Bg a r e h i g h l y schematized
n o d e i s f o r t h e c o n f i g u r a t i o n s corresponding t o / i / ,
,
r e s p e c t i v e l y , s e e r e f . (8) pp, 66.
/g
/,
and / a / ,
Column A r e p r e s e n t s succes-
s i v e shapes corresponding t o t h e lipht.hong/ia/ and column B
W
...
s i m u l a t e s t h e diphthong /is/.
Column C shows s u c c e s s i v e s t a g e s
.
F i g . 1-1
To i l l u s t r a t e c o a r t i c u l a t i o n e f f e c t s .
Colunr~s A and B a r e rnodols f o r t h e s u c c e s s i g e voc:.ll t r a c t
s h a p e s cltnri?g p r o d u c t i o n of d i p h t h o n g s /%a/ and /ca/,
r e s p e c t i v e l y . Column C x p r e s e n t s ,a p a l a t a l s t o p
C o l u ~ m sD and E a r e o b t a i n e d by s u p e r i m ? o s i ~ ? gt h e C-sequence of? t o p of the A- and 5 - s c q i ~ e n c ~ s .
gesture.
D a n d G r e p r e s e n t u t t e r a n c e s /iga/ and /iga/.
T h e model p r e d i c t s t h a t t h e v o c a l t r a c t shape a t t h e moment
of c l o s i ~ r e( ~ and
3 ~ 3 may
)
be d i f f e r e n t i n on? and t h e Sam-. syllabi? (/ig/) d e p e n d i ~ gon c o a r t i c u l a t i o n
.:-,.
.-.. *, 7
C-^
+^..+
,-A7 7
o f a n i d e a l i z e d /g/-closure;
Column D i s o b t a i n e d by s u p z r i m p o s i n g column C on
column A.
The D-sequence i l l u s t r a t e s t h e p r o d u c t i o n o f t h e
u t t e r a n c e /iga/.
Column E , f i n a l l y , i l l u s t r a t e s t h e u t t e r a n c e
It i s o b t a i n e d by s u p e r i m p o s i n g t h e C-sequence
/iga/.
of t h e B-sequence
.
on t o p
A l l t h e s e models a r e p h y s i o l o g i c a l l y o v e r s i m p l i f i e d
and s e r v e o n l y t h e purpose o f making more c o n c r e t e t h e i d e a of
superposit ion.
Non-invariance
of l o c i
One immediate consequence o f t h e p r e s e n t model i s
n o t e d when c o n f i g u r a t i o n D4 o f F i g , 1-1 i s compared w i t h conf i g u r a t i o n E3.
These two b o x e s c o r r e s p o n d t o t h e moment o f
c l o s u r e of t h e u t t e r a n c e s /i@/and /iga/,
r e s p e c t i v e l y , and
a r e hence b o t h l o c a t e d i n s i d e t h e s y l l a b l e /ig/.
however, q u i t e d i f f e r e n t from E3.
modes
D4 i s ,
It f o l l o w s t h a t t h e normal
o f v i b r a t i o n , o r f o r m a n t s , s h o u l d have d i f f e r e n t f r e -
q u e n c i e s i n t h e two c a s e s ,
I n o t h e r words, t h e l o c i o f t h e
formant t r a n s i t i o n s i n t h e s y l l a b l e /ig/ s h o u l d b e d i f f e r e n t
d e p e n d i n g on t h e n a t u r e of t h e f o l l o w i n g vowel,
The same s h o u l d b e t r u e f o r l o c i o f o n g l i d e t r a n sitions
(cv),
i f o u r model i s c o r r e c t .
D and E a r e w a d from bottom t o t o p .
T h i s i s s e e n i f columns
D4 and E3 w i l l t h e n
c o r r e s p o n d t o t h e moment o f r e l a a s e .
I n summary, o u r model p r e d i c t s t h a t a s t o p consonant f o -l l-c w- -~ c bl y c, f i x L d v o w ~ l( - C T T ) ::~.>g
b.-.,-.seocint:,cl w i t h ?.iff'~:r..nt 1r;ci f c r t h a
1;ff-gli6(, fr.;rm,?.nts cl..!;-:,n4in~;
..:.la(? 3: s t o i conaon,~it ;..rvc~c?.:cliby
g l i d t , f o r n z n t l a c 3 for c!iffuy;nt
s h o u l d be c o n t r a s t e d w i t h r e f . I
icIl..ntity ,:,f t k i E r r;..,:ing v o w a l ,
tl.
fix.,:!
r?
f;ilowinF:
~ i . t1~ (VC-)
.
h7.s d i f f s r s n t on-.
vow, 1 ~ T
. his 5t7t,mint
) whore i t i s s a i d t h a t
" s i n c e t h e a r t i c u l a t o r y p l a c e o f p r o d u c t i o n o f each c o n s o n a n t
i s , f o r t h e most p a r t , f i x e d , we might e x p e c t t o f i n d t h a t t h e r e
i s correspondingly a fixed frequency position
f o r i t s second formantl1,
... 'lorL t h e
-
or 'locus9
-
assumption t h a t t h e f i r s t
and second v o w e l s and t h e momants o f c l o s u r e and r e l e a s e of t h e
stop.
I n d u b i o u s c a s e s t h e l o c u s f r e q u e n c i e s were g u s s s s d ,
The
These measurements a r e summarized i n F i g , 1-2.
h o r i z o n t a l l i n e s w i t h vowel symbols o v e r them have been p l a c e d a t
t h e mean F2 f r a q u e n c i e s f o r e a c h o f t h s f o u r v o w e l s ,
l i n a s terminating i n dots represent
tions.
Th.e o b l i q u e
s c h e m a t i z e d formant t r a r , s i . -
Each t r a n s i t i o n i s b a s e d on two measuremen-ks.
The d i f f e r - .
ence between t h e t e r m i n a t i o n f r e q u e n c y of a formant t r a n s i t i o n and
t h e f r e q u e n c y o f t h e formant d u r i n g t h e s t e a d y p a r t of t h e vowel
i s g i v e n by comparing i n t h e f i g u r e t h e f r e q u e n c i e s o f t h e t e r m i n s l
d o t s w i t h t h o s e of t h e a s s o c i a t e d v o w e l s ,
L i n e s f a n n i n g out
towards t h e r i g h t mean o f f - g l i d e t r a n s i t i o n s and t h o s e f a n n i n g ou-t
towards t h e l e f t a r e o n g l i d e t r a n s i t i o n s ,
The i n t e r v o c a l i c s t o p s
a r e i n d i c a t e d a t t h e bottom o f t h e p i c t u r e which i s t h u s d i v i d e 2
i n t o t h r e e p a r t s , one f o r e a c h o f b, d, and g ,
ds a n example t h e o f f - g l i d e
from t h 3 vowel
b
i n t h e g-part
transitions i n the syllable
2nd formant t r a g s i t i o n s
of t h e f i g u r e ( i . e , t h e o f f - g l i d a
/bg/)
It i s s a e n
may b e s t u d i e d .
t h a t t h e t r a n s i t i o n i s f a l l i n g and ends a t 1250 c / s when t h e p o s t
s t o p vowel i s /u/,
When t h s pest s t o p vowel i s /y/, h o ~ q e v e r , t h e
t r a n s i t i o n i s s l i g h t l y r i s i n g and ends a t 7625 e / s .
=
375 c / s .
The rang.is of v a r i a t i o n f o r a l l ker;ni:lal
16%; - 1250
=
f'rcquencies
a r e s e e n i n T a b l e 1-2.
/ g/
of f - g l i d e
T a b l e 1-2.
/b/
/d/
ongli.de
off-glide
onglide
of f - - g l i d e
onglide
Rangc of v a r i a t i o n o f 2nd f o r z a n t l o c u s c / s .
I n t h i s experiment o n l y rounded voraels were u s e 6 i n
o r d e r t o m i n i m i z ~t h e ~ f f e c t so f changcs i n l i p - r o u n d i n g d u r i n g
t h e t r a n s i t i o n from t h e f i r s t vowel t o t h e l a s t vowel i n t h e
utterances.
It i s p o s s i b l e , however, t h a t t h e d i f f e r e n c e s i n
F i g . 1-2.
Yeixsure~nents on 2nd forinant t r a n s i t i n n s ill VCT ubtf-ranees
pr3d:rced by male s p e a k e r of SweJish. E a c h o f t h e ParA-like dr3wi1lgs
i i z d i c a t e s the r a n g e s of v a r i a t i o n o f termi:lal. 'requency ( " l o c u s q q )of
v a r i a t i o n seem; t o depend 03
s e c o n d f o ~ m m tn e a r t h e s t o p gap. Thi:;
c o a r t i c u l a t i o n a c r o s s the c o n s o n a n t .
See texl:.
lip-rounding
between /y/,
/b/,
/a/,
and /u/
t h a t s t i l l remain
c o n t r i b u t e i n p a r t t c t h e v a r i a t i o n observed i n T a b l e 1-2, r e f .
and
(8) pp. 82 and 280,
(3)
#This s h o u l d n o t i ~ v a l i d a t et h e i d e a
t h a t t h e s t o p g e s t u r e i s superimposed upon t h e vowel g e s t u r e s i n c e
t h e c h a n g e s i n l i p - r o u n d i n g a r e f e a t u r e s of t h e r e s p o n s e t o t h e
vowel p a r t o f t h e i n s - t r u c t i o n ,
On t h e c o i i t r a r y , t h e d a t a supper-t
t h e q u a l i t a t i v e c o a r t i c u l a t i o n modei d e s c r i b e d e a r l i e r i n t h i s
Tho p r e d i c t e d e f f e c t i s q u i t e l a r g e i n st l d a s t t h o r e l a - -
paper.
t i v e l y small material presented here.
F u r t h e r and n o r s e x t e n s i v ~
a c o u s t i c measurements a l o n g s i m i l a r l i n e s a r e p r e s e n t l y u n d e r way,
X-ray films
-
A s p a r t of a l e r g c r X-ray s t u d y grogram d e s c r i b e d
e l s e w h e r e i n t h i s QPSR a f i l m h a s been r e c c r d e d o f t h e p r e s e n t
a u t h o r s p e a k i n g among o t h e r t h i n @ , t h e u t t e r a n c e s /hy:dy:/,
/ha:da:/,
/hu:du:/,
/hyzgy:/,
/hagga:/,
/huzgu/
and /hy:ga:/,
The sonagrams o f t h e s i m u l t a n e o u s l y mads sound r e c o r d i n g s o f t h e s e
u t t e r a n c e s a r e shovn i n F i g . 1-4, The a r r o w s a t t h e b ~ t t o m sof
t h e s e sonagrams i n d i c a t e where t h e X-ray f i l m t r a c i n g s l a b e l e d
i n F i g , 1-3 have b e e n p i c k e d .
yga
They have a l l been chosen a s n c a r l y a s p o s s i b l e i n t h e m i d d l e of
d
d
d
g
g
g
y y Y a a' u u9 y y9 a a Y u u Y
t h e c l o s u r e i n t e r v a l except
Y
g
and
a
which c o r r e s p o n d s t o a f r a m e a t
t h e v e r y s t a r t o f c l o s u r e ( s e e arrow o f F i g . I--4),
The e x p o s u r e
t i m e p e r frame o f t h e motion p i c t u r e camera i s l e s s t h a n 10 msec,
The s3cond column from t h e l e f t of F i g , 1-3 shows,
f o r comparison t h e c o n f i g u r a t i o n s c o r r e s p o n d i n g t o t h e v o x e l s /ST/y
/a/, and /u/.
The second p i c t u r e cf t h 6 r i g h t m o s t column shows
t h e 'Ires-ting" o r , p e r h a p s , "stand-by" p o s i t i o n ,
f ~ t h e bottom
o f t h e same column i s shown a p i c t u r e o f a s q u a r e g r i d t a k e n
t h r o u g h t h e image i n t e n s i f i e r and camera system.
h e l d i n t h e m i d - s a g i t t a l p l z n e of' t h e s u b j e c t .
between a p a i r o f l i i l c s i n t h e g r i d i s 1 om.
The g r i d was
The r n a l d i s t a n c e
By u s i n g t h e l i t t l e
T-shaped makers around each p i c t u r e of F i g . 1-3 t h e d i s o r t e c l
g r i d p a t t e r n c a n 3 e employed f o r e x a c t d i s t a n c e mea.sureman.ts.
There a r e u s u a l l y t h r e e tongue c o n t o u r s i n t h e
tracing presented.
The i n n e r m o s t c o n t o u r r s p r e s e n t t h e t o n g u e Y s
iy , C-3.
1 I. l us t r i - t i n g t.!lr ef F e c t of a V-V e n v i r:,nmetlt oil t:1=:
s h a p e 3 f t h e t m g u e duritzg t h e a r t i c a I . 3 t i o n 0 4 a s t o p conso.=arlt
::l.osxre.
T h e r e i s no cclique t a r g e t c o f l f i g u r a t i o n c o r r e s p o n d i n g
t u tIze s t o p .
The g r i d p a t t e r n a t the lower r i g h t can be used
for 4i.:tarice rneasuren::nts.
P
--
-. - --
.
.
---
F i g . 1-4. Soiiagrams c o r r e ~ p o n d i i l g kc:, F i g . 1-3. The a r r o w s
i n d i c a t e t h e t i m e s a t w h i c h t h e X-ray p i c t u r e s were sampled.
Ths o t h e r two s h v i -t!~e o r i g z ~of t h i
midlin;!.
"
two c u s h i o n s t h a t o f t e n form -t:, tlze rigl1-i; 2 n d l:f-t
midline.
Ths ou5ermost o f tF,-=.so~ - d - g a ei z t h a t o;
- ---
of t'.e
iL
tC I I ~ L . L s
:ly
t h e su?;,jcct, s
r i g h t cushion,
i;onsir-'':*;-;,-:';<
...,.-
shape of t h s t o n g u e as a ~ f i h o l ai:!~;.:;r;.os
u
:Cs
!,2.:cj.;:.
2.-. c r
Comparison w i t h -the ~ ~ o a e l - s h e p eosf tlia ;coond cc;ld;;;i ind-ric.~,tcs
.
,
t h a t t h i s v p . r i a t i o n i s s u c h 3s t c as.;xn!~la'to t h e -k-oxdl,
.
1-t i s d i f f l o u l t
- ...-
a,voj-d. -!;he!2onr;l12.ci,ali at -2Izere
t3
ul?j.que -~;~r,yc?-(;
v o c ~ ~t rla c t c o n 5 y ~ - r e % i c , r
i s no s u c h t h i n g a s
a s s o c i a t o d w i t h t h z s t o p ? /d./
'
shou-ld n o t o b t a i n e i t h e r
arid /g,/
..
(>3i1st?ql;lzn.t.ly? ~'?S.o~uel o c i
a
%
I n t h e t r a a j - n g of
( e z t r e n e uype;
J
t o n g u e s h a p e s c o r r s s ; - , ~ n ? ' , i n g-to
<-
rre11t) i h u
( d c t t e d li:.ie> an1?
2
(dasked
a-a
l i n e ) h a v e b e e n superi!npor;-!d.
T
g, ~ h 3 , p e (ncl3.j-d i ~ n 3 )i s
y
i n t e r m e d i a t e b d t ~ r e e nthcsi- Swr;, T h i s s u g g t s t E - t h a t t h a ",n.wc-
;Y
f
LG
O
s h a p e h2s s t a r t o d t o agprcech t k c
o511.~3;73~f b!1k
fi>llo~r,ii.ng
/E/
t h e dat 2 o b t a i n e d Trorn form2.n'; frecruency I I ~ . R Z S I I . ?(:?~ Q4.).
~~E
It i s e x p e c t 22. --lha-t ;"~zll.cr a:cd mvra
a n a l y s e s of t h e X-ray f i l m s %illS;>Cin A
;;licz;i+.L.>-lf
ive
~ V EI ~ o ~ ci;15'0i;:i;l.t
;!
c o r n i n g t h e u s e f u l n e ; ~ o f t h e p e r e n $ mcdel
.
1 . e ~con--
Conclusion
Phonerces o ~ comr!io:cily
n
b e c h a r a c t e r i a e d slloi?atFca.il:/.
on t h e b a s i s c f in~.rc?.rian-t
audiLory- f e a t u r e s of c l a s s e s oi;' sp?cr:k
scunds.
It s e e m n a t u r a l t o loo!.:
of these invariailts
iil
f o r t h e p h y s i o l o g i c a l b:i,sis
-th- XGnner i n irl;ioh
u s e s c o n t e x t u a l assirnile-tion,
- l z , i k e ~2.dmi-ta a:lbz
The wo2k repo:cj;c-d k e r ~:.e e:-1
attempt i n t h i s d i r e c t i ~ n .
nins
i d e a s and d e t a ? - e s c r i b e d nbovc :?ng ? ~ ~ b ? - : :5s ~ 2
. .
s m m a r i z z d as f ~ l 1 . :o ~i t~ i s s u g g e s t ~ dt h a t t h ? eT;ls:al%f
o ~ g
,
mechanism i s c o ~ l t ~ g l i e'oyd tlla ner7rou.s sys?;cil c-:~? 2 - b i e n - ., ~-c-rz
i n d e p e n d ~ n t ( ? ) c!!arin41s.
On? o f t h c s c c h a n n e l s a c c q t s v c w e l s
i n s t r u c t i o n s and t h e o t h e r one s t o p consonant i n s t r u c t i o n s .
When a stop-vcwel
sequence i s t o b e produced t h e s t o p and vori-71
i n s t r u c t i o n s a r e impressed up03 t h e system r o u g h l y s i m u l t a n e o u s i y .
The s t n p i n s t r u c t i o n i s t h + n removed b s f o r e t h e v o x e l i n s t r u c t i o n .
lit t h e o u t p ~ l tend, e . g , ,
st t h e v o c a l t r a c t shepe l e v e l , t h e
speech s l g n a l appsars a s a mixture of t h c responses t o each o f
t h e two i n s t r u c t i o n s i n i s o l a t l c n ,
The i m p l i c n t i c n would n c c o r d i n g l y be t h a t t h e t i m s
u n i t c f n a t u r a l s p e e c h encoding i s i n c e r t a i n c a s s s more of t h e
s i z e of a s y l l a b l e t h a n of a phoneme.
T h i s , i f t r u e , mey p n r t l y
e x p l a i g tlio f a i l u r e o f a u t o m a t i s synthesis schemes i n which a
v o c a l t r a c t a n a l o g i s brought t o move from t a r g e t t o t a r g e t i n
a piece-wise l i n e a r f a s h i o n ( 1 0 )
References :
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