**5.2 Tympanometry**

It is the measurement of acoustic emissions in the external auditory meatus as a function of air pressure within the external auditory meatus. It provides a rapid atraumatic and objective technique for evaluating the integrity of (a) Middle ear transmission system, (b) Estimating middle ear pressure, (c) Estimating volume of ear canal or middle ear, (d) Evaluating Eustachian tube function.

Type A Tympanogram indicate normal middle ear pressure as indicated by tympanogram peak at 0 daPa. Normally middle ear pressure typically falls between +50 and –100 daPa.

Volume measurements more than 2 ml in children and 2.5ml in adults are usually indicative of tympanic membrane perforation or patent pressure equalization tube.

Mild cochlear hearing loss has little effect on acoustic reflex thresholds for tonal stimuli. for patients with hearing losses that exceed 70 dB reflexes are typically absent.
