Impulse response measurement of individual ear canals and impedances at the eardrum in man

kHz. Findy we give the theoretical and numerical solu­ tiOD for the "inverse problem" of calculating an arbi­ trary area function from its impulse response. To ex­ amine this method in practice some test measurements were performed with custom-made brass tubes which yield excellent results. Also the impedance values match well to the horn impedance which cou1d be calculated analytically. Individual results from the measurement of hu­ mans are reported for 8 subjects.. When their imped­ ances were transformed to a common reference plane by means of the actual area functions. the deviations between individual subjects were significantly re­ duced compared to the constant-tube assumption. The reference plane of the chosen tennination imped­ ance is 5 mm in front 01 the ear canal end quite near the beginning of the inclined eardrum The achieved results are in agreement with anatomical data and published values of the eardrum impedance.