[Limit of measurement of middle ear impedance (author's transl)]

The air volume enclosed in the acoustic duct is considered to be one of the causes of the bad reproductibility and the great scattering of measurement results of middle ear impedance. Therefore this volume was measured with ten subjects (20 ears) and the measured values of impedance were corrected. A procedure for determining the volume between the occlusion of the external canal and the ear-drum is described. The difficulties of carrying out this procedure are pointed out. Because of the volume determination for series examinations the measurement of the value of the impedance change as a criterion for individual resistance to noise of persons exposed to pulse noise involves great efforts and is therefore considered to be an inappropriate method as long as the indicated difficulties with measuring techniques continue to exist.