Weber Test - Detection of Conductive Hearing Loss

Detection of Conductive Hearing Loss

A patient with a unilateral conductive hearing loss would hear the tuning fork loudest in the affected ear. This finding is because the conduction problem of the middle ear (incus, malleus, stapes, and eustachian tube) masks the ambient noise of the room, while the well-functioning inner ear (cochlea with its basilar membrane) picks the sound up via the bones of the skull causing it to be perceived as a louder sound than in the unaffected/normal ear. Another theory, however, is based on the occlusion effect described by Tonndorf et al. in 1966. Lower frequency sounds (as made by the 256Hz fork) that are transferred through the bone to the ear canal escape from the canal. If an occlusion is present, the sound cannot escape and appears louder on the ear with the conductive hearing loss.

Conductive hearing loss can be mimicked by plugging one ear with a finger and performing the Rinne and Weber tests, which will help clarify the above. Humming a constant note and then plugging one ear is a good way to mimic the findings of the Weber test in conductive hearing loss. The simulation of the Weber test is the basis for the Bing test.