Some alternative methods for the measurement or determination of the human eardrum impedance

The uncertainties in the measurement of the eardrum impedance at low frequencies due to the microphone placement and/or due to the transfer function of the source can be avoided through the use of a velocity‐controlled source, combined with a single pressure measurement at the source. Due to the reciprocal spreading between the source size and the number of higher order acoustic wave components, the source should be of as large a diameter as possible. At high frequencies, the eardrum impedance can be determined via pressure measurements with a half‐wavelength long microphone, of arbitrary cross‐sectional area, which distorts neither the measured (plane wave) pressure nor the eardrum pressure. Schemes for the absolute calibration for such a measuring system will be described also.