Aim and Objectives

This test is done to compare the auditory acuity of each ear to bone and air conduction. It helps to detect the type and degree of hearing loss. It is interpreted in association with Weber test.

Procedure:

• The procedure is first explained to the patient. The tuning fork is stuck gently so as not to produce overtones and disharmonics. It can be stuck against a rubber pad or any bony prominence of the examiner.
• The vibrating tuning fork is held about 1 inch away from the ear, such that the prongs are parallel to the external auditory canal.
• The patient is asked to indicate when he stops hearing the sound. When he indicates so, the tuning fork is immediately placed on the mastoid cortex. If the patient does not hear sound on the mastoid cortex it indicates, air conduction is better than bone conduction.

2) WEBER TEST

The Weber test is a useful, quick, and simple screening test for the evaluation of hearing loss. The test can detect unilateral conductive and sensorineural hearing loss.

Procedure of Weber test:

• Verbal consent should be gained prior to performing the test.
• Clear instructions should be given to the patient to avoid misinterpretation of the test.
• A tuning fork generally consists of the tines (the U-shaped prongs), the stem, and the footplate.
• Hold the tuning fork by the stem between the thumb and first finger.
• In the 7th month, this plug dissolves and the epithelial lining of the floor of the meatus participates in formation of the definitive eardrum.
• Strike the tines one-third of the way from the free end of the prong onto a firm but the elastic object (e.g., the clinician’s knee or elbow). This will produce a relatively pure tone.
• Avoid striking the tines onto a hard surface as this may damage the tuning fork and produce multiple overtones.
• Ask the patient whether it is heard loudest in either one side or the midline (e.g., “Is the sound louder in your right ear, left ear, or the middle?”)

Fistula Procedure

Pressure changes in the external auditory canal are brought by applying intermittent pressure on the tragus or by Siegel’s speculum. In a normal person the test is negative because the pressure changes cannot be transmitted into the labyrinth .

Interpretation:

• In fistula over the dome of lateral semicircular canal increased pressure causes conjugate horizontal deviation of eye to the normal side. As pressure is maintained jerk nystagmus develops with the fast component towards the affected ear.
• Fistula of lateral semicircular canal (anterior to the ampulla) causes deviation of eyes to the affected side.
• Vestibular erosion causes rotatory horizontal nystagmus towards the diseased ear.
• Fistula of the posterior semicircular canal causes vertical movements of eyes.
• A positive fistula also implies that the labyrinth is still functioning.