Description du sujet de thèse

The thesis project is part of the ANR AVATARS "Artificial Voice production: control of bio-inspired port-HAmilToniAn numeRical and mechatronic modelS" (2023-2027). This ambitious collaborative research project between several French laboratories (IRCAM Paris, GIPSA-lab Grenoble, LMA Marseille, 3SR Grenoble and LPL Aix-en-Provence) and the University Hospital of Liège in Belgium has the overall objective of developing a new approach to human voice production based on physical modelling, non-linear systems theory and innovative mechatronic and material science designs, in order to reproduce the human vocal behaviour measured in healthy and pathological voices and to achieve a deeper understanding of their specificities. The first objective is to design theoretical and mechatronic voice avatars: numerical avatars based on physical modelling and simulation, and bio-inspired mechatronic avatars based on technological development and robotics. The second objective is to analyse and control phonation, focusing on the oscillatory regimes involved in the different vocal qualities and registers in singing voice, and to validate them by comparing them to human biological signals in vivo. Regime analysis (automated mapping, bifurcation analysis) aims to provide a "user manual" for avatars. The control methods aim at generating principal gestures to achieve features related to speech expressivity and articulation.

This thesis project aims to explore the complex physical phenomena involved in human vocal production and to reproduce human vocal behaviour in spoken and sung expressions on an instrumented bench. A first robotic bench has already been developed (Henrich et al., 2022). It consists of a laryngeal duct containing flexible and deformable vocal folds coupled to a variable geometry vocal duct. This bench allowed the characterisation of the vibratory behaviour of several homogeneous structures, designed on the basis of elastomers or hydrogels, capable of mimicking the macroscopic mechanical properties of the vocal fold and of oscillating in a self-sustained manner by fluid-structure interaction (Yousefi-Mashouf, 2022).
In this thesis, the impact of acoustic coupling (acoustic loading by a vocal tract reproducing oral vowels) on the self-oscillation of existing biomimetic vocal folds will be explored in a first step. The acoustic loading will first consist of simple geometric vocal tracts representing vowels, and then of morpho-realistic 3D-printed vocal tracts based on MRI images of the same vowels. Finally, in connection with the development by the mechatronics team of the GIPSA-lab laboratory of a robotic vocal tract capable of articulating speech by actuating the jaw, tongue and lips, the phonatory behaviour will be characterised during co-articulated sequences.
In a second phase, improvements will be made to the vibrator. The structure, material type and geometry of the biomimetic vocal folds will be varied to explore their impact on phonatory behaviour. In particular, vocal folds with a bi-layer fibrous structure will be developed and tested, based on promising first results (Yousefi-Mashouf, 2022).
The characterisation of the self-oscillating behaviour of biomimetic vocal folds in fluid-structure-acoustic interaction will be done by aerodynamic measurements of air pressure and flow, acoustic measurements from the radiated sound wave, and by image analysis obtained by highspeed cinematography. The optical method of stereo-correlation of digital images will also be used to characterise the deformation of the vibrating structure in 3D, using the know-how of the 3SR laboratory and the highspeed cameras present on the bench. The use of a conductive silicone will also be envisaged to allow measurement of the glottal contact on a model by electroglottography, a very common technique for characterising this contact in humans

Contexte de travail

The Gipsa-lab is a joint research laboratory of the CNRS, Grenoble-INP -UGA and the University of Grenoble Alpes. It is under agreement with Inria and the Observatory of Sciences of the Universe of Grenoble. He conducts theoretical and applied research on AUTOMATICS, SIGNAL, IMAGES, SPEECH, COGNITION, ROBOTICS and LEARNING.
Multidisciplinary and at the interface between the human, the physical and digital worlds, our research is confronted with measurements, data, observations from physical, physiological and cognitive systems. They focus on the design of methodologies and algorithms for processing and extracting information, decisions, actions and communications that are viable, efficient and compatible with physical and human reality. Our work is based on mathematical and computer theories for the development of models and algorithms, validated by hardware and software implementations.
By relying on its platforms and partnerships, Gipsa-lab maintains a constant link with applications in a wide variety of fields: health, environment, energy, geophysics, embedded systems, mechatronics, processes and industrial systems, telecommunications, networks, transport and vehicles, operational safety and security, human-computer interaction, linguistic engineering, physiology and biomechanics, etc.
Due to the nature of its research, Gipsa-lab is in direct and constant contact with the economic environment and society.
Its potential as teacher-researchers and researchers is invested in training at the level of universities and engineering schools on the Grenoble site (Grenoble Alpes University).
Gipsa-lab develops its research through 16 teams or themes organized into 4 divisions:
• Automatic and Diagnosis (PAD)
• Data Science (PSD)
• Speech and Cognition (PPC)
• Geometries, Learning, Information and Algorithms (GAIA).
The staff supporting research (38 engineers and technicians) is distributed in the common services distributed within 2 divisions:
• The Administrative and Financial Pole
• The Technical Pole
Gipsa-lab has around 150 permanent staff, including 70 teacher-researchers and 41 researchers. It also welcomes guest researchers and post-docs.
Gipsa-lab supervises nearly 150 theses, including around 50 new ones each year. All the theses carried out in the laboratory are financed and supervised by teacher-researchers and researchers, including 50 holders of an HDR.
Finally, around sixty Master's trainees come each spring to swell the ranks of the laboratory.

Contraintes et risques

Constraints: respect for laboratory hours, work on a shared platform
Risks: work with a laser vibrometer