The abc's of impedance audiometry

Abstract Impedance audiometry plays an important part in the otologic evaluation. To appreciate fully when it can be of help, the otologist must have a basic understanding of the impedance bridge and acoustic equivalent volume. The test battery consists of a tympanogram, the determination of acoustic impedance and eliciting the acoustic reflex. Impedance audiometry is of greatest value in young children because a voluntary response is not required. The otologist may differentiate conductive from sensori‐neural impairments. In the adult it has been of most use as part of the neuro‐otologic evaluation, to help differentiate a cochlear from a retrocochlear impairment.