What is a Weber's test?
Weber's test is screening test for detecting hearing loss. It can detect unilateral (one-sided) conductive and one-sided sensori-neural hearing loss.
How is Weber's test done?
A vibrating tuning fork of 512 Hz frequency is placed on the patient's vertex or forehead or upper central incisor. The patient is asked to identify in which ear he can hear the sound better.
512 Hz frequency tuning fork is chosen for the above test because:
a) It falls in the mid speech frequency
b) Overtones and vibrations are minimal.
How is Weber's test interpreted?
1. In a normal patient, the sound is equivocally heard in both ears
2. In conductive deafness: Sound lateralises to the ear having worse hearing
3. In sensori-neural deafness: Sound lateralises to ear with better hearing. This is due to the Stenger's phenomenon.
Stenger's phenomenon states that when two tones of equal frequencies are presented simultaneously to two ears, the tone is heard only in the ear in which it is louder. Thus lateralization to the better ear indicates that there is sensorineural impairment in the poorer ear or the poorer ear has conductive impairment with a bone conduction threshold worse than the threshold of the better ear. Lateralization to the poorer ear indicates conductive impairment in the poorer ear.