Gelles test is done in?

(a) OtosclerosisRef: Dhingra Text book of ENT, 6th ed., ch-4* Gelle's 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 Siegle's 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.* Gelle's test is performed by placing a vibrating fork on the mastoid while changes in air pressure in the ear canal are brought about by Siegle's speculum.* Gelle's 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.