Impedance audiometric study of children. Comparison of impedance tympanoscope ZS 330 with impedance audiometer ZO 73 A.

In order to compare the impedance audiometer ZO 73 A with the impedance tympanoscope ZS 330 (both from Madsen Electronics), we examined 50 children who had been admitted to the ENT Department and 24 children from a kindergarten. There proved to be a good correlation between the middle ear pressure, except that ZO 330 showed a rather lower middle ear pressure. As regards compliance too there was a good correlation. The ipsilateral stapedial reflex was rather labile, and in 68% of the ears the two instruments showed conformity, while in 15% only ZO 73 A and in 17% only ZS 330 could elicit the reflex. When the middle ear pressure was lower than -100 mmH2O, the ipsilateral stapedial reflex could be elicited in only 25% of the cases, even though the middle ear pressure was equalized.