Coupling between ear canal and eardrum in model systems
Michael R. Stinson, Shyam M. Khanna · The Journal of the Acoustical Society of America · 1988
This paper examines a theoretical model of sound propagation in the ear canal that accounts for the distributed acoustical load presented by the eardrum. This model is an extension of our previous one-dimensional formulation [S. M. Khanna and M. R. Stinson, J. Acoust. Soc. Am. 77, 577–589 (1985)], which was limited to rigid-walled canals. The spatially varying motion of the eardrum enters as a driving term in the equation for the sound field. In principle, this present model can be combined with detailed, dynamical models of the tympanic membrane. Experiments using model canals are underway to test the theory. In these, the sound field is determined with the eardrum replaced by either a mechanically driven piston or a passive, locally reacting load. Preliminary results indicate that the theoretical formulation can describe the sound field in the cat ear canal up to at least 25 kHz and in the human ear canal up to at least 15 kHz.