articulatory assymetries in speech production

ARTICULATORY ASSYMETRIES IN SPEECH PRODUCTION Jo

1,2 Verhoeven ,

Naomi

1 Miller ,

Carlos

3 Reyes-Aldasoro

1Division

of Language and Communication Science, Phonetics Laboratory, City University London, UK 2Computational Linguistics and Psycholinguistics Research Centre, University of Antwerp, Belgium 3Department of Electrical and Electronic Engineering, City University London, UK • STARTING POINT OF THIS STUDY

PROPORTION OF ASYMMETRICAL ARTICULATIONS •

ASSUMPTION THAT ARTICULATION IS SYMMETRICAL IN THE TRANSVERSE PLANE OF THE VOCAL TRACT. DURING ARTICULATION TONGUE CONTACT ON THE RIGHT SIDE OF THE PALATE IS EQUALLY LARGE AS ON THE LEFT SIDE. HOWEVER, PALATOGRAMS OFTEN SHOW ASYMMETRICAL TONGUE-PALATE CONTACT. [y]

OBSERVATION 1: THERE ARE TWICE AS MANY ASYMMETRICAL ARTICULATIONS AS

C O M PA R E D

TO

OFTEN

THE

TOWARDS

LEFT .

THE

ASYMMETRIES IN TONGUEPA L AT E

C O N TA C T

Total contact: 0.081

!

[P]

75

OF SPEECH.

37

50

SEEM

INHERENT IN THE ARTICULATION Total contact: 0.387

100

ASYMMETRY IS SLIGHTLY MORE

[u]

25

46

THIS IS CONSISTENT

! WITH PREVIOUS RESEARCH IN

16

0 ASYMMETRICAL

MARCHAL ET AL. (1988)

[P]

Right

THE

ONES.

SYMMETRICAL

Left

SYMMETRICAL

ASYMMETRY AND PLACE OF ARTICULATION • OBSERVATION 2: Total contact: 0.177

Total contact: 0.177

!

[i]

[E]

[I]

[Y]

THE ASYMMETRY IS BIGGER IN ! A N T E R I O R A R T I C U L AT I O N S . ANTERIOR ARTICULATIONS ARE

•

Total contact: 0.194

Total contact: 0.274

Total contact: 0.194

!

!

MORE

ASYMMETRICAL

THAN

Retroflex

IS CONSISTENT WITH PREVIOUS

Palatal

OBJECTIVE OF THIS STUDY

RESEARCH !

THIS

(MARCHAL !ET AL.,

1988) AND MAY BE EXPLAINED BY THE GREATER FLEXIBILITY OF

TO DOCUMENT ARTICULATORY ASYMMETRIES ON THE BASIS OF PREVIOUSLY PUBLICHED PALATOGRAMS WITH THE AIM OF ILLUSTRATING TONGUE-PALATE

RIGHT

Alveolar

S I G N I F I C A N T LY

POSTERIOR ARTICULATIONS. Total contact: 0.419

LEFT

THE ANTERIOR PORTION OF THE

Velar -0,03

-0,023

-0,015

-0,008

0

0,008

0,015

0,023

0,03

TONGUE.

CONTACT DURING THE ARTICULATION OF SPEECH SOUNDS IN A WIDE VARIETY OF LANGUAGES, SPEAKERS AND CONTEXTS.

ASYMMETRY AND MANNER OF ARTICULATION •

• METHODOLOGY

OBSERVATION 3:

1. COLLECTION OF PALATOGRAMS

A SYMMETRY IS BIGGEST IN FRICATIVES. MAY HAVE TO DO

COLLECTED PALATOGRAMS IN PREVIOUSLY PUBLISHED RESEARCH ARTICLES FROM 5 RESPECTED PROFESSIONAL JOURNALS SINCE 1970, REPRESENTATIVE OF A NON-CLINICAL ADULT POPULATION.

WITH

C R E AT I N G

LEFT

RIGHT

Plosive

S U I TA B L E

AERODYNAMIC CONDITIONS FOR

Nasal

THE TURBULENCE OF FRICATIVES

(PROJECTING THE AIRSTREAM AWAY

FROM

THE

Fricative

MIDLINE

TOWARDS THE TEETH). IT IS NOT Lateral Approximant CLEAR WHY NASALS SHOULD BE RUNNERS UP.

Approximant -0,04 -0,03 -0,02 -0,01

2. CALCULATED INDEX OF ASYMMETRY

OF

ASYMMETRY

0,01 0,02 0,03 0,04

DISCUSSION:

MARCHAL, A., FARNETANI, E., HARDCASTLE, J., BUTCHER, A. (1988). CROSS-LANGUAGE EPG DATA ON LINGUAL ASYMMETRY. JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, SUPP.1, VOL. 84, S127.

DIRECTION

0

SIZE

OF

ASYMMETRY

SEVERAL EXPLANATIONS ARE POSSIBLE. IN THE FIRST INSTANCE AN ANATOMICAL EXPLANATION SHOULD BE CONSIDERED IN THAT ASYMMETRIES MAY ARISE AS A RESULT OF THE CURVATURE OF THE SPEAKER’S PALATE: THE TONGUE TOUCHES THE PALATE FIRST WHERE THE PALATE DESCENDS TO A GREATER EXTENT.

THIS IS PRESENTLY BEING INVESTIGATED BY SCANNING SPEAKERS’

PALATES, MODELLING ANATOMICAL ASYMMETRIES BY MEANS OF BIOMEDICAL IMAGING TECHNIQUES AND RELATING THOSE TO ARTICULATORY ASYMMETRIES.

Ias = (Na - Nb) / (Na + Nb) HIGHER

NEGATIVE

VALUES HAVE MORE CONTACT ON THE LEFT

VALUES INDICATE A BIGGER DIFFERENCE BETWEEN LEFT AND RIGHT

• RESULTS

225 SPEAKERS

1502 PALATOGRAMS

42 % MALE (N = 94) 49 % FEMALE (N = 111) 9 % UNSPECIFIED (N = 20)

11 LANGUAGES: SPANISH ENGLISH NORWEGIAN JAPANESE ITALIAN GREEK GERMAN FRENCH CROATIAN TAMIL CATALAN

OTHER POTENTIALLY INTERESTING EXPLANATIONS ARE MOTOR DOMINANCE (ASYMMETRIES ARE MORE TOWARDS THE RIGHT IN RIGHT-HANDERS AND MORE TOWARDS THE LEFT IN LEFTHANDERS; HAMLET, 1987) OR HEMISPHERIC DOMINANCE FOR LANGUAGE. IN THE LATTER CASE ASYMMETRIES ARE MORE TOWARDS THE RIGHT. AS A RESULT OF LATERALISATION THERE IS A MORE DIRECT NEURAL ROUTE TOWARDS THE MUSCLES ON THE RIGHT SIDE OF THE TONGUE. BOTH ASPECTS NEED TO BE INVESTIGATED IN MORE DETAIL. REFERENCES: HAMLET, S., BUNNELL, H., STRUNTZ, B. (1986). ARTICULATORY ASYMMETRIES. JOURNAL AMERICA, 79, 1164 - 1169.

OF THE

ACOUSTICAL SOCIETY

OF

HAMLET, S. (1987). HANDEDNESS AND ARTICULTORY ASYMMETRIES ON /S/ AND /L/. JOURNAL OF PHONETICS, 15, 191-195.

3 VARIETIES OF SPANISH 5 VARIETIES OF ENGLISH AMERICAN AUSTRALIAN BRITISH CANADIAN SCOTTISH

MARCHAL, A., FARNETANI, E., HARDCASTLE, W.J., BUTCHER, A. (1988). CROSS-LANGUAGE EPG ASYMMETRY. JOURNAL OF THE ACOUSTICAL SCOEITY OF AMERICA, VOL 81, S127.

DATA ON LINGUAL

ARGENTINIAN CUBAN PENINSULAR

2 VARIETIES OF CATALAN • MAJORCAN VALENCIAN

THIS WORK WAS FUNDED BY A LEVERHULME TRUST RESEARCH PROJECT, GRANT RPG-2017-054