21. Investigations Audiometric Tests: Includes: 1. Pure – tone Audiometry (PTA) which is most commonly used used for measuring hearing acuity. 2. Tympanometry which provides a quick objective measurement of the state of the middle ear.
22. Radiography Plain X-Ray; of the temporal bone show the degree of pneumatization of the mastoid , clouding of the air cells can indicate infection while area of erosion may be seen in cholesteatoma , malignant disease. CT-SCAN ; is now widely used specially in complicated otitis media, in revision surgery.