Abstract: In an acoustic impedance meter used for evaluating the performance of the middle ear and tympanic membrane system; a sound source is coupled to the ear canal by means of an ear probe and a sound sensor in conjunction with an inverse feedback system maintains a constant sound intensity in the ear canal regardless of ear canal compliance. An analog voltage, derived from the sound source excitation, is thereby representative of ear canal compliance. A pump is provided to moderately pressurize or evacuate the ear canal to determine the variation in compliance under various test pressures. An acoustic stimulus generator may be used to elicit an acoustic reflex response and a storage and comparison circuit derives an analog voltage representative of this acoustic reflex response.