Efforts and coordination of speech gestures

Disciplines: Acoustic phonetics, Biomechanics, Physiology, Cognition

Laboratory: GIPSA-lab, Grenoble

Supervision: Maëva Garnier, Pascal Perrier, Franck Quaine

Duration: 3 years (starting between Sept and Dec 2014)

Contact: maeva.garnier@gipsa-lab.grenoble-inp.fr / +33 4 76 57 50 61

Context: This Ph.D thesis takes part to the ANR project StopNCo, dealing with the characterization

and understanding of the physiological efforts and the gesture coordination in speech production1.

Stop consonants (/p/, /t/, /k/, /b/, /d/ or /g/) are of particular interest for the study of speech motor

control, as they require a precise coordination of breathing, laryngeal and articulatory gestures in their

force and timing.

General questions: Stop consonants

are created by an occlusion of the vocal

tract that can occur at 3 different “places

of articulation” in French: at lips (for /p/

and /b/), just behind the teeth (for /t/ and

/d/) or at the back of the palate (for /k/

and /g/) (see Figure). The release of this

occlusion creates a short explosion noise

(or “burst”) and a quick variation in

frequency of the vocal tract resonances

(“formant transients”). These acoustic

features differ significantly between the 3

places of articulation

The objectives of the project are to characterize and to model:

1. by which coordination of breathing and articulatory gestures we control the finer variation of these

acoustic cues (burst spectrum and formant transients)?

2. how these cues are modified when speakers speak more clearly and try to enhance the perceptual

contrast between these 3 places of articulation?

3. how this control develops in children and can dysfunction in some of them?

4. how this control can vary in efficiency, i.e. in the ratio between the acoustic outcomes and the

physiological efforts?

Program:

The first step of the project will consist in implementing new methodologies to measure lip and

tongue articulation efforts, using surface electromyography (EMG), force sensors and electromagnetic

articulography (EMA) (see next figure).

1

see http://www.agence-nationale-recherche.fr/en/anr-funded-project/?tx_lwmsuivibilan_pi2%5BCODE%5D=ANR-14-CE30-

0017

Multiple EMG electrodes will be placed

around the lips to characterize the muscle

activity in different speech movements

and to find global descriptors of the

degree of articulation effort and fatigue.

Force sensors will be used, searching their

optimal number and position on the lips

and palate. We will also try to characterize

the tongue and lips stiffness in order to

take account of it in the calibration of the

force measurements.

Finally, the articulation force estimated by

these two methodologies will be

confronted to the velocity peaks of

tongue and lip movements measured with

EMA, as well as to the perceptual selfevaluation

of the effort spent by the

subject.

The Ph.D thesis will base on these methodologies to characterize the coordination of breathing,

laryngeal and articulatory gestures in the production of stop consonants in healthy adult speakers. A

large database will be recorded with synchronous physiological and acoustical signals, on several

speakers, in controlled laboratory conditions, and for a variety of voice qualities and efforts (whisper to

shout, slow to fast speech rate, etc.). Using statistical data processing and mapping techniques, you

will establish a functional model able to predict the variation of acoustical outcomes from the covariation

of physiological parameters.

In a second step, a second experiment will be conducted in a more realistic and interactive situation

of face-to-face communication. You will explore how speakers modify their production of stop

consonants when they communicate in noisy or reverberant environments, and how they consequently

modify the coordination and the effort of their speech gestures, in comparison to casual speech.

Collaborations

The project will take place at GIPSA-lab in Grenoble, under the co-supervision of Maëva Garnier

(Expert in speech and cognition), Pascal Perrier (Expert in Speech motor control) and Franck Quaine

(Expert in biomechanics and EMG signals), in close relationship with the medical field (a dentist and a

maxillofacial surgeon).

The Ph.D thesis will belong to a larger project, involving a second team that works on laryngeal efforts

(including a ENT specialist), and a third team working on the development of this coordination in

children (including speech therapists from Grenoble’s hospital). These two teams will use the

methodologies developed during the beginning of the Ph.D. thesis, and will bring complementary

information to the functional model of stop consonants production.

During the Ph.D. thesis, we envisage to send the Ph.D candidate for about 3 months in Italy for a

collaboration on high-density EMG matrices.

Skills: We are looking for an open-minded student, coming from either an engineering background

(electronics, mechanics, acoustics) or a human sciences background (phonetics, cognitive sciences),

but having in any case at least some basic technical skills (programming, signal and data processing)

and a strong interest in human-related questions (physiology, speech, human interaction). An

experimental approach will be appreciated.

Indemnities: 1400 € per month during the 3 years of Ph.D fellowship. The Ph.D candidate will be

able to have additional teaching activies.