An eardrum impedance simulator for use with physical replicas of the human ear canal.

An eardrum impedance simulator has been incorporated into life‐size replicas of the human ear canal. The simulator branches off from the ear canal at the center of the nominal eardrum position. It has been designed so that sound pressure distributions in an ear canal will have the same standing wave ratios as those measured previously in human subjects over the 4–10‐kHz range. The key component of the eardrum simulator is a micro‐perforated plate, whose holes provide damping through viscous and thermal boundary layer losses. The optimum design specifies 109 holes of 0.06 mm diameter in 0.003‐in. shim stock. Measurements of sound pressure distribution in replica ear canals are underway to evaluate the acoustical performance of the eardrum simulator. The sound field is generated by an occluding hearing aid test fixture.