Finite Element Method Analysis of Occluded-Ear Simulator and Natural Human Ear Canal
In this paper, we discuss the propagation of sound in the narrow pathways of an occluded-ear simulator typically used for the measurement of insert-type earphones. The simulator has a standardized frequency response conforming to the international standard (IEC60318-4). In narrow pathways, the speed and phase of sound waves are modified by viscous air damping. In our previous paper, we proposed a new finite element method (FEM) to consider the effects of air viscosity in this type of audio equipment. In this study, we will compare the results from the ear simulator FEM model, and those from a three dimensional human ear canal FEM model made from computed tomography images, with the measured frequency response data from the ear canals of 18 people.
 IEC60318-4, IEC standard, Simulators of human head and ear - Part 4: Occluded-ear simulator for the measurement of earphones coupled to the ear by means of ear inserts 2010.
 M. Sasajima, T. Yamaguchi, and A. Hara, “Acoustic Analysis Using Finite Element Method Considering Effects of Damping Caused by Air Viscosity in Audio Equipment,” Applied Mechanics and Materials, vol. 36, pp. 282–286, 2010.
 M. Sasajima, T. Yamaguchi, M. Watanabe, Y. Koike, “FEM Analysis of Occluded Ear Simulator with Narrow Slit Pathway,” International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering vol. 9, No.9, pp. 1430-1433, 2015.
 M. A. Biot, “Theory of propagation of elastic waves in a fluid-saturated porous solid. I. Low-frequency range,” Journal of Acoustical Society of America, vol. 28, pp. 168–178, 1956.
 M. A. Biot, “Theory of propagation of elastic waves in a fluid-saturated porous solid. II. Higher-frequency range,” Journal of Acoustical Society of America, vol. 28, pp. 179–191, 1956.
 T. Yamaguchi, “Approximated calculation to damping properties of a closed sound field involving porous materials(proposal of a fast calculation procedure for model damping and damped response),” Transactions of the Japan Society of Mechanical Engineers, Series C, vol. 66, no. 648, pp. 2563–2569, 2000.
 T. Yamaguchi, H. Nakamoto, Y. Kurosawa, and S. Matsumura “Finite element analysis for damping properties of sound-proof structures having solid body, porous media and air,” Transactions of the Japan Society of Mechanical Engineers, Series A, vol. 69, no. 677, pp. 34–41, 2003.
 T. Yamaguchi, J. Tsugawa, H. Enomoto, and Y. Kurosawa, “Layout of Sound Absorbing Materials in 3D Rooms Using Damping Contributions with Eigenvectors as Weight Coefficients,” Journal of System Design and Dynamics, vol. 4-1, pp. 166–176, 2010.
 T. Yamaguchi, Y. Kurosawa, and H. Enomoto, “Damped Vibration Analysis Using Finite Element Method with Approximated Modal Damping for Automotive Double Walls with a Porous Material,” Journal of Sound and Vibration, vol. 325, pp. 436–450, 2009.