In an ear with a conductive hearing loss, the air conduction is decreased, and the masking effect is therefore diminished. This tends to mask the sound of the tuning fork heard by bone conduction. In normal conditions, there is considerable background noise, which reaches the tympanic membrane by air conduction. The explanation for the Weber test effect is based on the masking effect of background noise. The Weber test is illustrated in Figure 11-13.

You have created a conductive hearing loss on the right by blocking the right canal the sound is lateralized to the right side.

Occlude your right ear and place a vibrating tuning fork in the center of your forehead. Sound is lateralized to the affected side in conductive deafness. If the sound is not heard in the middle, the sound is said to be lateralized, and thus a hearing loss is present. Hearing the sound, or feeling the vibration, in the middle is the normal response. Ask the patient to indicate whether he or she hears or feels the sound in the right ear, in the left ear, or in the middle of the forehead. Stand in front of the patient and place a vibrating 512-Hz tuning fork firmly against the center of the patient's forehead. In the Weber test, bone conduction is compared in both ears, and the examiner determines whether monaural impairment is neural or conductive in origin.

Weber tuning fork used for