1 AN INTERPRETATION OF PATTERNS OF VCV COARTICULATORY DIRECTION ACCORDING TO A MODEL OF ARTICULATORY...

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AN INTERPRETATION OF PATTERNS OF VCV COARTICULATORY DIRECTION

ACCORDING TO A MODEL OF ARTICULATORY CONSTRAINTS

Daniel Recasens

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INTRODUCTION

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Research goal

The major goal of this study is to gain a better understanding of the direction of coarticulatory effects in VCV sequences.

VCV coarticulation is a complex scenario involving C-to-V and V-to-C/V effects which may be

anticipatory (C-to-V1, V2-to-C/V1),carryover (C-to-V2, V1-to-C/V2).

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V1 C V2

C-to-V1

V2-to-V1

C-to-V2

V1-to-V2V2-to-C

V1-to-C

Coarticulatory interactions in VCV sequences

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The present study deals with patterns of V-dependent coarticulatory direction at the tongue dorsum, and with the implications for our understanding of phonemic planning and sound change.

It argues that those patterns may be accounted for within the framework of the degree of articulatory constraint (DAC) model of coarticulation (Recasens, Pallarès and Fontdevila, 1997).

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DAC model

Vs and Cs are assigned different DAC values depending on their production conditions and on their coarticulatory behavior (see Öhman, 1966 and Bladon and Al-Bamerni, 1976 for related notions).

Empirical data indicate that DAC values (and, therefore, the degree of articulatory constraint) should vary with tongue body activation according to several parameters:

articulatory displacement e.g., // > /n/;

aerodynamic requirements e.g., trills, fricatives > other Cs;

double articulation e.g., velarized alveolars > plain alveolars;

articulatory coupling e.g., laminoalveolars > apicoalveolars.

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DAC scale

DAC value Vowels Consonants Rationale

4 ---------- /s, , , r/ Strict manner requirements, double articulation

3 /i/ (Alveolo)palatals Maximal tongue dorsum raising

2 /e, / Dentals,alveolars Moderate tongue dorsum raising

1 /a, , o, u/ ------------- Tongue dorsum-postdorsum coupling

0 // Labials No lingual activation

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Predictions regarding coarticulation

(1) The degree of coarticulation between adjacent Vs and Cs is directly related to the DAC difference between the two consecutive phonetic segments. E.g.,

(C-to-V coarticulation) /a/ > /ta/, since the DAC diffference is 2 for /a/ (3-1) and 1 for /ta/(2-1).

(V-to-C coarticulation) /ip/> /it/, since the DAC difference is 3 for /ip/ (3-0) and 1 for /it/ (3-2).

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(2) The degree of coarticulatory sensitivity for a given V or C varies inversely with its DAC value. The graph plots MCD or mean coarticulatory distance index values for Cs differing in DAC (MCD= F2iCi- F2aCa / 2).

MCD value

l n s rl

2 2 2 2 3 4 4 4 43

DAC value

0

100

200

300

400

500

600Hz

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Main hypothesis regarding coarticulatory direction

There should be an inverse relationship between V effects and C effects at the temporal site where the two conflict with each other, i.e., between

- V1 carryover and C anticipation,

- V2 anticipation and C carryover.

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V1 carryover conflicts with C anticipation

V1 C

C-to-V1 V1-to-C

V2 anticipation conflicts with C carryover

C V2

C-to-V2V2-to-C

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Moreover, the degree of V coarticulation is conditioned bythe degree of C coarticulation (which is in line with Cs but not Vsbeing required to achieve a closure or constriction):

(a) V1 carryover should increase as C anticipation decreases.

(b) V2 anticipation ought to vary inversely with the strength of the C carryover effects.

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METHODOLOGY

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Data sample

This research is based on Catalan and Spanish data reported basically in the papers

Recasens, D., Pallarès, M.D. and Fontdevila, J. (1997) A model of lingual coarticulation based on articulatory constraints, JASA, 102, 544-561.

Recasens, D. (1987) An acoustic analysis of V-to-C and V-to-V coarticulatory effects in Catalan and Spanish VCV sequences, JPh, 15, 299-312.

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F2 patterns of coarticulatory direction will be presented for VCV sequences with the Vs /a/ and /i/, and with several Cs differing in DAC value. As shown for each C condition in the list below, VCV sequences were uttered by a variable number of speakers, had different stress patterns, and were meaningful or nonsense.

Sequences

alveolopalatal // 2 Cat VCV (meaningful)

alveolopalatal // 5 Cat VCV (nonsense)

alveolopalatal // 5 Cat VCV (nonsense)

alveolar dark /l/ 6 Cat VCV (meaningful, 1 Cat)

VCV (nonsense, 5 Cat)

alveolar clear /l/ 2 Sp VCV (meaningful)

alveolar trill /r/ 6 Cat, 2 Sp VCV (meaningful, 2 Sp, 2 Cat)


alveolar tap // 6 Cat, 2 Sp VCV (meaningful, 2 Sp, 2 Cat)


dental // 2 Cat, 2 Sp VCV (meaningful)

alveolar /n/ 5 Cat VCV (nonsense)

alveolar /s/ 5 Cat VCV (nonsense)

speakers stress meaningful/nonsenseC condition

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Experimental procedure

Pairs of asymmetrical and symmetrical VCV sequences involving V anticipatory or carryover coarticulation as a function of changing /a/ vs /i/. This allows measuring separately V effects from /a/ and V effects from /i/.

Anticipatory effects from /a/ /iCi/-/iCa/ pair with changing V2 and fixed V1=/i/

Carryover effects from /a/ /aCi/-/iCi/ pair with changing V1 and fixed V2=/i/

Anticipatory effects from /i/ /aCa/-/aCi/ pair with changing V2 and fixed V1=/a/ Carryover effects from /i/ /iCa/-/aCa/ pair with changing V1 and fixed V2=/a/.

V coarticulatory effects have been measured and evaluated statistically at C midpoint.

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Hz

1000

1500

2000

2500

1000

1500

2000

2500

Time (ms)

050 -50 0-50 50

V1 carryover V2 anticipation

Example

/VV/ pairs with changing /i/ vs /a/ and fixed /i/.

V C C V

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RESULTS

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Alveolopalatals

C effects often favor the carryover direction since alveolopalatals are more constrained at closure offset than at closure onset.

Laminopredorsal / (DAC=3)

Closure onset exhibits a coarticulation-sensitive, /n/-like linguopalatal contact configuration. Closure release proceeds backwards, thus leaving a coarticulation-resistant, /j/-like linguopalatal contact configuration at closure offset.

Closure onset Closure offsetClosure midpoint

(a) (a)

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Given that C effects often favor the carryover direction, the DAC model predicts that V effects should take place mostly at the carryover level. This means that we ought to find a stronger influence of V1 on C than of V2 on C.

Rationale: C carryover should block V2 anticipation to a larger extent than C anticipation blocks V1 carryover.

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All Catalan speakers under analysis (6 for //; 2 for //) show (a) more V1 carryover than V2 anticipation in each fixed V condition,(b) maximal V1 carryover from /a/.

Size of V effects

(X value in Hz across speakers)

0

50

100

150

200

250

300

350

400

Anticipation (from /a/)Carryover (from /a/)

Anticipation (from /i/)Carryover (from /i/)

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Coarticulatory effects for the individual speakers (//)

Size of V effects(in Hz)

-100

0

100

200

300

400

500

DR JP JS DP JC

-200

Anticipation (from /a/)Carryover (from /a/)

Anticipation (from /i/)Carryover (from /i/)

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F2 trajectories for asymmetrical /VV/ sequences exhibit larger F2 lowering effects from /a/ on // at more unconstrained closure onset than at more constrained closure offset.

Closure offset

C V2V1

0-100 100

1000

1500

2000

2500Hz

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Fricative // (DAC=4)In comparison to /, /, prominent anticipatory activity associated with frication should prevent V1 carryover effects from occurring. Consequently, the DAC model predicts that // should favor no specific V coarticulatory direction.

0

50

100

150

200

250

300

350

400

Size of V effects


Anticipatory (from /a/)Carryover (from /a/)

Anticipatory (from /i/)Carryover (from /i/)

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There is less carryover coarticulation as a function of V1=/a/ at C onset in sequences with // than in those with //.

Time (ms)

C V2V1

0-100 100

ai

ia

0 100-100

V1 C V2

1000

1500

2000

2500

Hz

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Apical /l/ produced with active tongue dorsum lowering (DAC=4)

Dentals, alveolars

C effects favor the anticipatory direction since /l/ is more constrained at closure onset than at closure offset.

The production of // involves tongue dorsum lowering in anticipation to tongue tip raising during the preceding V1 (Sproat and Fujimura, 1994).

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maximum contact

contact decrease associated with //

contact increase

Vowel /i/

Consonant

(C) (V)

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Given that C effects favor the anticipatory direction, the DAC model predicts that V effects ought to favor anticipation. This means that we ought to find a stronger influence of V2 on C than of V1 on C.

Rationale: C anticipation should block V1 carryover to a larger extent than C carryover blocks V2 anticipation.

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All 6 Catalan speakers under analysis exhibit (a) more V2 anticipation than V1 carryover in each fixed V condition,(b) maximal V2 coarticulation from /i/ (also from /a/).

0

50

100

150

200

l

Size of V effects




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-200

-100

0

100

200

300

400

500

PL DR JP JS DP JC



31

Hz 2500

2000

1500

1000ali

ila

Time (ms)

0-100 100

V1 C V2

F2 trajectories for asymmetrical /VV/ sequences show larger F2 raising effects from /i/ on /l/ at C offset than at C onset.

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Apicals /l, , / involving no active tongue dorsum lowering (DAC=2)

Tongue tip raising favors C anticipation. C effects are small due to the flexibility of the tongue tip articulator and to little tongue tip-tongue dorsum coupling for /l, , /.

C anticipatory effects of little prominence ought to allow large V1 carryover effects. The DAC model predicts that V1 carryover should prevail over V2 anticipation in this case. This means that there should be a stronger influence of V1 on C than of V2 on C.

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All speakers under analysis (2 Spanish for /l/; 2 Spanish and 2 Catalan for //; 2 Spanish and 6 Catalan for //) show

(a) more V1 carryover than V2 anticipation as a general rule,(b) maximal V1 coarticulation from /i/ (also from /a/).

l 0

200

400

600

800

Size of V effects




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0

200

400

600

800

1000

FM CAS PL DR JP JS DP JC




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Time (ms)

1000

1500

2000

2500Hz

V1 C V2

ai

ia

F2 trajectories for asymmetrical /VV/ sequences exhibit larger V effects from /i/ (F2 raising) and /a/ (F2 lowering) at C onset than at C offset.

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Fricative /s/ (DAC=4)

Frication blocks V coarticulation. In comparison to /l, , /, prominent tongue front raising anticipation for /s/ is expected to prevent much V1 carryover from taking place.

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Consequently, the DAC model predicts that V1 carryover ought to prevail upon V2 anticipation to a lesser extent in VCV sequences with /s/ than in those with /l, , /.

l 0

200

400

600

800

Size of V effects


s



38

Hz

1000

1500

2000

2500

V1 C V2

ai

ia

Time (ms)

0 100-100

asi

isa

V1 C V2

There is less V1 carryover coarticulation as a function of /i/ (F2 raising) and /a/ (F2 lowering) at C onset in VCV sequences with /s/ than in those with //.

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THEORETICAL IMPLICATIONS

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(a) If reflecting phonemic planning, the onset of V2 anticipation should be fixed independently of the articulatory requirements for the phonetic segments preceding V2 (Fowler and Saltzman, 1993).

(b) The offset of V1 carryover is expected to be more variable, if conditioned by the inertial properties of the phonetic segments following V1.

Articulatory organization

Extensive VCV coarticulation data reported in this paper allows testing two central hypotheses about articulatory organization in speech production:

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Regarding prediction (a), results show that V2 anticipatory effects are not equally prominent across C conditions and thus, do not begin at the same moment in time. Instead, there is more V2 anticipation for less constrained Cs than for more constrained ones.

rsl n l

Hz

0

200

400

600

800Anticipatory (from /i/)

Anticipatory (from /a/)

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s rl n l

Carryover (from /i/)

Carryover (from /a/)

rsl n l

Hz

0

200

400

600

800Anticipatory (from /i/)

Anticipatory (from /a/)

Regarding prediction (b), results show that V1 carryover effects are more variable than V2 anticipatory effects. Indeed, the green line in the right graph is steeper than the green line in the left graph.

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While being in disagreement with a strict version of the fixed window planning hypothesis, our findings are in support of the following notions:

(a) anticipatory effects do reflect phonemic planning,

(b) in comparison to anticipatory effects, carryover effects are more largely conditioned by the ongoing mechanical constraints.

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Moreover, there ought to be a close relationship between the direction of assimilatory processes and the direction of related coarticulatory effects such that

prominent anticipatory effects may give rise to regressive assimilations,

prominent carryover effects may result in progressive assimilatory processes.

Sound change

Assimilatory processes may originate from prominent coarticulatory adaptations between consecutive phonetic segments.

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Syllable final /l/ favors regressive V assimilations since it is presumably darker than syllable initial /l/ and therefore, is expected to exert more C anticipation than C carryover. (Consistent with the DAC model).

// > Catalan [l] < Latin PĬLU// > Ardenne [] < Latin BĔLLA// > Old French [] < Latin CAPĬLLOS// > Piedmontese [] < Latin PALU

C-to-V assimilation and coarticulation

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(Alveolo)palatal Cs may cause a following V to undergo assimilatory fronting and raising since carryover C-to-V effects are specially prominent in this case. (Consistent with the DAC model).

// > W. Catalan [] Latin IENUARIU

// > W. Catalan[Port. charao

// > W. Catalan [] Latin IOANNE

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Labial Vs cause regressive labialization in non-labial Cs presumably because lip rounding effects are more prominent at the anticipatory vs carryover level. (Consistent with the DAC model).

/g/ > b, vdial. Spanish [axa] < Spanish [auxa] Campanian [favola] < Italian [fagola]

V-to-C assimilation and coarticulation

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A palatal V or glide may trigger regressive and progressive C palatalization since prominent C coarticulatory effects in tongue dorsum raising and fronting occur both leftwards and rightwards. (Consistent with the DAC model).

Changes: /k, t/ > c/(t)(t)s /l/> /n/ > /s/ >

Examples: Regressive Italian [tnto] Latin CENTUCatalan [sen] Latin CENTU

Haute Loire [cia] Latin TIRAREFrench [li] Latin LINEA

Bergün [ik Latin LUCEArdenne [e] Latin SEX

Progressive Romansh [satts] Latin SACCU Spanish [note] < [nojte] Latin NOCTEdial. Catalan [kua] < [kujna] Latin COCINALunigiana [avrio] Latin APRILEJudeo-Spanish [se < [sejs] Latin SEX

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V-to-V assimilation and coarticulation

V-to-V coarticulatory effects are smaller than coarticulatory effects involving adjacent phonetic segments (i.e., C-to-V, V-to-C).

An analysis of lexical variants from a Catalan database reveals the existence of regressive rather than progressive V-to-V assimilations independently on the intervocalic C, which suggests that listeners pay more attention to V-to-V anticipation than to V-to-V carryover as a general rule. (Not consistent with the DAC model).

// > W. Catalan [] TENERE

//> W. Catalan [ RENIONE

// > W. Catalan [] TǓSSIRE

/a/ > Occitan [] LACERTU

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Regressive V lowering and raising may be triggered by an entire CV sequence where anticipatory effects exerted by the C and the V appear to reinforce each other. (Consistent with the DAC model regarding the C influence).

V lowering// > , W. Catalan [] Latin SILENTIU //> W. Catalan [] Latin DELICATU

V raising// > W. Catalan [] Latin LEGERE//> W. Catalan [] Latin SAGINU//> W. Catalan [Latin COLLIGERE

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CONCLUSIONS

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Patterns of V coarticulatory direction in VCV sequences may be predicted from patterns of C coarticulatory direction. The latter are conditioned by the production requirements and the DAC degree for the consonant.

The DAC model contributes to a better understanding of the principles of articulatory organization underlying phonemic planning and causing assimilatory processes to occur.

Stress does not seem to affect patterns of VCV coarticulatory direction substantially, i.e., VCV sequences with Cs such as /l/ and // exhibit the same V coarticulatory direction independently on whether stress is placed on V1 (VCV) or on V2 (VCV).

Syllable affiliation (which is invariably (V)(CV) in Catalan) does not appear to play a major role either. It has been shown that V effects favor the anticipatory or carryover direction depending on the articulatory characteristics and the degree of constraint for the intervocalic C.

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REFERENCESBladon, R.A.W. and Al-Bamerni, A. (1976) Coarticulation resistance in English /l/, JPh,

4, 137-150.

Fowler, C.A. and Saltzman, E.(1993) Coordination and coarticulation in speech production, L &S, 36, 171-195.

Öhman, S. (1966) Coarticulation in VCV utterances: spectrographic measurements, JASA, 39, 151-168.

Recasens, D., Pallarès, M.D. and Fontdevila, J. (1997) A model of lingual coarticulation based on articulatory constraints, JASA, 102, 544-561.

Recasens, D. (1987) An acoustic analysis of V-to-C and V-to-V coarticulatory effects in Catalan and Spanish VCV sequences, JPh, 15, 299-312.

Sproat, R. and Fujimura, O. (1993) Allophone variation in English /l/ and its implications for phonetic implementation, JPh, 21, 291-312.

ACNOWLEDGEMENTSThis research has been funded by projects BFF2003-09453-C02-01 (Ministry of Education of Spain) and 2001SGR00425 (Catalan Government).

I would like to thank P. Prieto, J. Romero and M.J. Solé for comments.

1 AN INTERPRETATION OF PATTERNS OF VCV COARTICULATORY DIRECTION ACCORDING TO A MODEL OF ARTICULATORY...

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