Measurement of the acoustic input immittance of the human ear

A method is presented for measuring acoustic immittance (admittance or impedance) in the human ear canal and its validity is demonstrated for frequencies from 62 Hz to 4 kHz. Special attention is given to estimating the residual ear-canal space between the eardrum and the tip of the measuring device; estimates were determined, in part, using immittances measured with static pressures applied in the ear canal. Immittance estimates at the eardrum are reported for four normal subjects. Below 500 Hz, the immittance is compliance dominated. Our averaged compliance equivalent to 0.70 cc agrees with that reported by others. From 1 to 4 kHz, the immittance is resistance dominated. Our resistance values exceed those generally reported previously; they are, however, similar to those of Mehrgardt and Mellert [J. Acoust. Soc. Am. 61, 1567--1576 (1977)] and to values suggested from analysis of other acoustical measurements on the external ear.