Analyse numérique et expérimentale des déformations du conduit auditif humain liées à l’activité de la mâchoire

Abstract

In-ear technologies (wireless headphones, digital hearing protectors, hearing aids, etc.) also called "hearables" are spreading massively and rapidly in our professional and personal lives. Thus, interest in improving the design of earplugs for better comfort and retention has increased in recent years. In addition, with the ever-increasing computing power and functionality, the battery life of these technologies remains a challenge. Studies have shown that the earcanal is deformed by the temporomandibular joint during daily activities such as chewing or speaking. This dynamic movement of the earcanal may be a promising source of energy for future in-the-ear technologies. However, the anatomical relationship between the earcanal and the jaw is not yet fully understood, especially as in vivo measurements are made difficult by the complexity of the earcanal anatomy and the invasiveness of the associated procedures. This manuscript-based thesis presents a study in three main steps, two of which are focused on a constituent of the "jaw-ear" system and the third of which deals with the relationship between the two. In the first stage, a model of the kinematics of the TMJ and more particularly of the mandibular condyle is developed. This is based on a two-phase motion generation synthesis allowing the design of a six-bar kinematic simulator reproducing the motion of the mandibular condyle. Then, the deformation modes of the earcanal during 4 activities of the face, the head and the jaw are investigated. Morphological measurements of earcanal impressions from 18 participants suggest that actions such as smiling and opening the mouth cause the greatest deformations, particularly near the entrance and in the middle of the two earcanal bends. Finally, a biomechanical coupling model between the earcanal and the mandibular condyle using a numerical and experimental approach is proposed and validated. The model includes an anatomical earcanal cavity surrounded by elastic cartilage and an ellipsoidal mandibular condyle. The modeling of the cartilage-bone junction, the position of the mandibular condyle and the behavior of the surface in contact with the concha are the three coupling parameters considered. Numerical validation is performed with finite element analysis while physical validation is possible with a jaw simulator and a 3D printed artificial earcanal. This thesis explicitly details the methods and knowledge developed to model the deformations of the earcanal under the effect of the jaw movement. A better knowledge of the biomechanics of the earcanal thanks to the characterization of the deformations (localization, type, intensity) will allow a more precise evaluation of the power capability of the earcanal in a context of in-ear energy harvesting. The results obtained as well as the models developed will also benefit the improvement of the geometry of the earplugs in terms of comfort and retention.

Date	26 Mar 2024
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Jérémie Voix (Supervisor)