On the asymmetry of susceptance tympanograms

The origin of the tail asymmetry of susceptance tympanograms was investigated. A flow-measuring device enabled an accurate determination of ear-canal volume changes produced during tympanometry. From these measurements one finds that not only is the asymmetry due to the earcanal volume change but that finite drum susceptances exist at high transtympanic pressures. This residual susceptance was found to differ in the two tails of the tympanogram. Although no absolute values of those drum susceptances can be computed, it is possible to indicate which pressure side has the greater residual susceptance.