In Bing test, on alternately compressing and releasing the external acoustic meatus, the sound increases, and decreases. This indicates

Tests for bone conduction TestPrincipleMethodImpressionBing test Examines the effect of occlusion of ear canal on hearing Tuning fork placed on mastoid while examiner alternatively closes & opens the ear canal by pressing on the tragus inwards Patient hears louder when ear canal is occluded & softer when ear canal is open - Normal persons or sensorineural deafness ( Bing + ve )No change on ear canal opening or occlusion - conductive deafness ( Bing - ve )Gelle's test Examines the effect ofincreased air pressure in ear canal on hearing Placing a vibrating fork on mastoid while changes in air pressure in ear canalare brought about by siegel's speculum Positive - normal persons or sensorineural deafnessNegative - ossicular chain fixed or disconnected(Refer: PL Dhingra, Textbook of Ear, Nose, Throat, 6thedition,pg no: 21,22,23)