Bing's test; occlusion test. Test used to distinguish between conductive and sensorineural hearing losses. A vibrating tuning fork is placed on the center of the subject’s forehead and the external acoustic meatus is gently occluded. If the ear is normal or if there is a pure sensorineural hearing loss present, the loudness to a low-frequency stimulus is increased, but if there is a conductive hearing loss there is no change in loudness.