Optimality-Theoretic modelling of phoneme split

Paul Boersma, University of AmsterdamPaola Escudero, McGill University

EuroSLA 11, Paderborn September 26, 2001

Six hypothesesabout phonemic contrasts

¿ Their production is dialect-dependent.¿ Their perception is dialect-dependent.¿ L1 learners achieve optimal perception

given their production environment.¿ This can be modelled by Optimality Theory

and the Gradual Learning Algorithm.¿ L2 learners do not necessarily achieve

optimal perception.¿ This can also be modelled by OT & GLA.

We test these six hypotheses on the English /I/-/i/ contrast

L1: Scottish Standard EnglishL1: Southern English Standard EnglishL2: Spanish-speaking learners of English

Adult native Scottish production

260

300

400

50050 60 90 120 150 180

Duration (ms)

Adult native Southern production

260

300

400

50050 60 90 120

Duration (ms)

Six hypothesesabout phonemic contrasts

Their production is dialect-dependent.¿ Their perception is dialect-dependent.¿ L1 learners achieve optimal perception.¿ This can be modelled by OT & GLA.¿ L2 learners do not necessarily achieve

optimal perception.¿ This can also be modelled by OT & GLA.

Adult native perception

Dur. (ms), reliance 34.6%83 177

480

344

Dur. (ms), reliance 10.6%83 177

480

344

Scottish Southern

Six hypothesesabout phonemic contrasts

Their production is dialect-dependent. Their perception is dialect-dependent.¿ L1 learners achieve optimal perception.¿ This can be modelled by OT & GLA.¿ L2 learners do not necessarily achieve

optimal perception.¿ This can also be modelled by OT & GLA.

Why does perception have to depend on the production environment?

Answer: to optimise perception, the listener has tominimise the probability ofperceptual confusion

The optimal perception strategy, therefore, is:likelihood maximisation, i.e.choose the most likely produced category,given a certain F1 & duration

Average production environment:260300

400

50050 60 90 120 ms

/I/

/i/

260300

400

50050 60 90 120 ms

/I//i/

Optimal perception (max. likelihood):260300

400

50050 60 90 120 ms

/i/

/I/

260300

400

50050 60 90 120 ms

/i/

/I/

87.1% 82.5%

Scottish Southern

Six hypothesesabout phonemic contrasts

Their production is dialect-dependent. Their perception is dialect-dependent. L1 learners achieve optimal perception

(they integrate the two acoustic cues).¿ This can be modelled by OT & GLA.¿ L2 learners do not necessarily achieve

optimal perception.¿ This can also be modelled by OT & GLA.

Native English constraint set

“260 Hz should not be perceived as /I/”

“260 Hz should not be perceived as /i/”

“500 Hz should not be perceived as /I/”

“500 Hz should not be perceived as /i/”

“60 ms should not be perceived as /I/”

“60 ms should not be perceived as /i/”

“180 ms should not be perceived as /I/”

“180 ms should not be perceived as /i/”

…and so on, for all F1 and duration values

Average production environment:260300

400

50050 60 90 120 ms

/I/

/i/

260300

400

50050 60 90 120 ms

/I//i/

Optimal perception (max. likelihood):260300

400

50050 60 90 120 ms

/i/

/I/

260300

400

50050 60 90 120 ms

/i/

/I/

87.1% 82.5%

Scottish Southern

Scottish optimal perception in OT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[349 Hz,

74 ms]

349 Hz

not //74 ms

not //74 ms

not //349 Hz

not // // *! *

// * *

[349 Hz,

74 ms]

349 Hz

not //74 ms

not //74 ms

not //349 Hz

not // // * *

//

*! *

Southern optimal perception in OT

How is the knowledge acquired?

Whenever the listener makes a categorization error, she applies a Gradual Learning Algorithm:

 

 

 

 

 

 

[349 Hz,

74 ms]

349 Hz

not //74 ms

not //74 ms

not //349 Hz

not //

// * *

// *! *

Simulated Scottish L1 development

baby 4 months 1000 months

50.0% 85.3% 87.0%

260

300

400

50050 70 90 120

dur.rel. -0.3%260

300

400

50050 70 90 120

dur.rel. 13.8%260

300

400

50050 70 90 120

dur.rel. 8.4%

(optimal: 87.1%)

Simulated Southern L1 development

baby 4 months 1000 months

50.0% 79.7% 82.5%

260

300

400

50050 70 90 120

dur.rel. -0.3%

(optimal: 82.5%)

260

300

400

50050 70 90 120

dur.rel. 48.3%260

300

400

50050 70 90 120

dur.rel. 68.2%

Six hypothesesabout phonemic contrasts

Their production is dialect-dependent. Their perception is dialect-dependent. L1 learners achieve optimal perception. This can be modelled by OT & GLA.¿ L2 learners do not necessarily achieve

optimal perception.¿ This can also be modelled by OT & GLA.

Typical L2 categorization by Spanish learners of English

Scotland Southern Englandmf

dur.rel. -5.7%

83 177480

344

mtdur.rel. -10.0%

83 177480

344

efdur.rel. 85.7%

83 177480

344

ofdur.rel. 98.6%

83 177480

344

Six hypothesesabout phonemic contrasts

Their production is dialect-dependent. Their perception is dialect-dependent. L1 learners achieve optimal perception. This can be modelled by OT & GLA. L2 learners do not necessarily achieve

optimal perception.¿ This can also be modelled by OT & GLA.

Native Spanish constraint set“260 Hz should not be perceived as /i/”“260 Hz should not be perceived as /e/”“260 Hz should not be perceived as /a/”“260 Hz should not be perceived as /o/”“260 Hz should not be perceived as /u/”low ranked or non-existent:“60 ms should not be perceived as /i/”“60 ms should not be perceived as /e/”“60 ms should not be perceived as /a/”“60 ms should not be perceived as /o/”“60 ms should not be perceived as /u/”

…and so on, for all F1 and duration values

Constraint set of Spanish learners of English“260 Hz should not be perceived as /i/”“260 Hz should not be perceived as /e/”“260 Hz should not be perceived as /a/”“260 Hz should not be perceived as /o/”“260 Hz should not be perceived as /u/”

“60 ms should not be perceived as /short/”“60 ms should not be perceived as /long/”

…and so on, for all F1 and duration values, but:

no F1-to-/length/ mappings;

no duration-to-/vowel quality/ mappings.

Strategy of a Spaniard in Scotland

Two-category assimilation: English /i/ L2 /i/ English // L2 /e/

mtdur.rel. -10.0%

83 177480

344

mfdur.rel. -5.7%

83 177480

344

Simulation of a Spaniard in Scotland

200 months 204 months 1000 months

74.9% 83.5% 87.2%

(optimal: 87.1%)

260

300

400

50050 70 90 120

dur.rel. -0.2%260

300

400

50050 70 90 120

dur.rel. -0.1%260

300

400

50050 70 90 120

dur.rel. 0.3%

Strategy of a Spaniard in S.England

New length contrast: English /i/ L2 /i:/ English // L2 /i/

ofdur.rel. 98.6%

83 177480

344

efdur.rel. 85.7%

83 177480

344

Simulation of a Spaniard in S.England

200 months 204 months 1000 months

50.0% 79.0% 79.3%

260

300

400

50050 70 90 120

dur.rel. -0.3%

(optimal: 82.5%)

260

300

400

50050 70 90 120

dur.rel. 99.2%260

300

400

50050 70 90 120

dur.rel. 90.8%

Six hypotheses, now finally confirmed by us,

about phonemic contrasts

Their production is dialect-dependent. Their perception is dialect-dependent. L1 learners achieve optimal perception. This can be modelled by OT & GLA. L2 learners do not necessarily achieve

optimal perception. This can also be modelled by OT & GLA.

Native S.English has12 arbitrary symbols:

A possible assimilation patternSpanish S.English has2x5 vowels (7 symbols):

— i —

—

— e

— o

— u

— —

—

—

Discussion GLA generally leads to optimal perception,

but it depends on the appropriateness of the constraint set.

L2 learners seem to have constraint sets that are too restricted for the new language environment.

The restricted constraint set does not seem to cause the L2 learner much harm.

Adding a new contrast on the basis of duration seems to be easier than splitting existing vowel quality categories.

Thank you for your attention!