The Weber test is a screening technique used to determine whether a patient has a hearing loss in one of his ears. A tuning fork generates a tone which travels to the patient’s eardrum through the bones of the face. If the patient hears a softer sound or one that dissipates sooner in one ear or the other, it is an indication of hearing loss.
A simple and quick screening test, the Weber test is used to check for asymmetrical hearing loss, rather than hearing loss that occurs equally in both ears. In this test, a tuning fork is struck and then placed along various places on the midline of the patient’s skull. If the test results are normal, the subject will hear the sound of the tuning fork equally in both ears, both in terms of the duration of the sound and the intensity of it.
If the patient hears the sound of the tuning fork differently between the two ears it can be a sign of either conductive or sensorineural hearing loss. In conductive hearing loss there is a problem with the ear canal’s ability to conduct sound waves through to the eardrum. The condition is usually caused by an obstruction, whether from a foreign body, an ear infection, a tumor, or another cause.
Screening with the Weber test will show increased hearing in the ear affected by conductive hearing loss. Though this may seem counterintuitive, the ear with conductive hearing loss is able to hear the tuning fork through the bones of the face because the sound does not have to travel through the air in the ear canal. Sound waves that normally travel through the air, along the ear canal, are obstructed in cases of conductive hearing loss. The ambient sounds in the test room are muted in the affected ear, which makes the sound waves traveling through the bones of the Weber test subject’s face seem more intense in this ear.
The other type of hearing loss, sensorineural hearing loss, will show the opposite results in a Weber test. In this type of hearing loss, there is a problem with the nerves in the ear, the parts of the ear responsible for hearing, or the center of the brain devoted to hearing. The affected ear is not better able to hear sound conducted through the bones because the trouble isn’t in delivering sound waves to the eardrum but rather in processing those sound waves once they arrive.