<prompt> Gelles test is done in?OtosclerosisSerous otitis mediaTraumatic hearing lossAge related hearing loss  <response>: a OtosclerosisRef: Dhingra Text book of ENT, 6th ed., ch-4 Gelles test It is a test of bone conduction and examines the effect of increased air pressure i n ear canal on the hearing. Normally, when air pressure is increased in the ear canal by Siegles speculum, it pushes the tympanic membrane and ossicles inwards, raising the intralabyrinthine pressure and causing immobility of basilar membrane and decreased hearing, but no change in hearing is observed when ossicular chain is fixed or disconnected. Gelles test is performed by placing a vibrating fork on the mastoid while changes in air pressure in the ear canal are brought about by Siegles speculum. Gelles test is positive in normal persons and in those with sensorineural hearing loss. It is negative when ossicular chain is fixed or disconnected.It was a popular test to find out stapes fixation in otosclerosis but has now been super-ceded by tympanometry. 