Impedance matching by the. combined effects of the outer and middle ear

When the impedance mismatch between air and the oval window is computed by considering the latter as a small piston in a baffle, and taking the appropriate source impedance into account, it can be shown that the mismatch is frequency dependent and may be greater than 50 dB at 100 Hz. The middle ear transformer by itself is inadequate to compensate for the loss of transmission due to the mismatch. Only at the frequency of the outer ear resonance does the combined action of the outer ear and the middle ear produce an estimated gain that roughly compensates for the loss of energy at the interface. Detailed computations are shown for cats, and some results applicable to the human ear are also included.