Validation using the IN-VIVO experiment of the 3D model of the human ear using the equivalent mechanical impedance of the mass-spring-damper system.

The ear is the organ responsible for the perception of hearing. Its role is to amplify, transmit and convert an acoustic wave present in the environment into an electrical pulse that can be interpreted by the brain using the auditory nerve. There are different types of hearing loss, such as conductive hearing loss, sensorineural hearing loss, or mixed hearing loss, which is a combination of the first two. Conductive deafness, the type we are interested in this work, is related to a dysfunction of the middle ear, leading to an interruption of the progression of the sound wave within the hearing organ. This type of deafness is caused by impulse noise which is found in a large number of professional environments. The objective of this research is the creation of a 3D model of the human ear in order to characterize these noises to evaluate the auditory risks they induce in professional environment, to identify the means to protect oneself as well as possible. This 3D model of the human ear was developed using the Comsol Multiphysics software. The structure-acoustic interaction between the ear canal as a propagation field of the acoustic wave and the ear structures consisting of skin, cartilage, bone and tympanic membrane was solved using finite element analysis (FEA). We modeled the ossicular chain, the middle ear cavity and the cochlea by the equivalent mechanical impedance of a mass-spring-damper system. The results obtained show that the maximum displacements of the umbo are obtained in the frequency range of [1.7, 2.6] kHz, the sound pressure gain had the shape of a peak with a maximum at a frequency of 3 kHz. The displacement of the umbo depends on the damping coefficient d. The sound pressure at the tympanic membrane was increased compared to that at the entrance of the ear canal. These results were validated by the experimental results using the IN-VIVO experiment.