The measurement of the acoustical input impedance of human ears

As a contribution to current attempts at the international standardisation of artificial ears, an investigation has been carried out on the difficulties of measuring real ear impedance. A number of unexpected variations in the impedance, both long and short term, have been discovered not all the causes of which have been established. Other factors affecting the impedance are discussed and recommendations made regarding measuring conditions.

The results of this study are being used as the basis of a statistical survey of impedance over the telephonic frequency range.