Hearing Protection for High-Noise Environments. Attachment 5: Construction of the Human Head Model

A precise model of the cochlea and its vicinity is essential for reliable numerical simulation which could discern between different mechanisms of energy transfer to the human ear. Therefore, a significant fraction of our effort was devoted to the construction of a sufficiently detailed and anatomically faithful model of the ear its outer, middle, and inner parts. The model we constructed consists of the following parts 1 the outer ear represented by its exterior surface, the surface of the auditory canal including the tympanic membrane, modeled as a finite-thickness surface 2 the middle ear, modeled as a surface of the system of ossicles and supporting structures 3 the inner ear, modeled as a set of surfaces representing the boundaries of the cochlea, the vestibule, and the semi-circular canals 4 the skull, described by the surface of the bone 5 the outer surface of the skin surrounding the skull and 6 a homogeneous material filling the space between the skull and the inner ear. For tests of noise-protection devices, we also included a model of a helmet and the material layer filling the space between the helmet and the surface of the head. We stress that all the geometry components -- skull, skin, inner ear, middle ear, outer ear, and helmet -- are mutually compatible and matched to one another. Some representative examples of the geometry details are presented in Figures 1 to 8.