CLINICAL EXAMINATION OF HEARING

1. Clinical Speech Test: It is a simple test to assess the degree of hearing loss (HL) i.e. whether mild, moderate or severe.
2. Tuning Fork Tests: They are simple tests to assess the type of hearing loss (HL) i.e. whether conductive or sensori-neural.

• The Tuning Fork:
• Made of Stainless steel, having a base, stem, and two prongs.
• Frequency used: Commonest 256 and 512 Hz.
• Activation : The prongs are struck on a firm surface as the elbow or patella .

Principle:

It compares hearing by air conduction (AC) with hearing by bone conduction (BC) in the same ear by the same stroke of the tuning fork.

• During hearing by air conduction: Sound passes through the external ear ≫ Middle ear ≫ inner ear.
• Therefore, it takes the advantage of middle ear amplification.
• During hearing by bone conduction: Sound passes directly to the inner ear without passing through the external or middle ear.

• Therefore, it does not take the advantage of middle ear amplification.

Method:

• To test hearing by AC, the prongs of the vibrating tuning fork are placed near the external canal .
• To test hearing by BC, the base of the vibrating tuning fork is placed on the mastoid process .

Results:

• Normal hearing: AC better than BC ≫ Rinnè positive.

• Conductive HL: BC better than AC ≫Rinnè negative.

• Sensory-neural HL: AC better than BC, but both are reduced ≫ reduced Rinnè positive

N.B. Unilateral severe Sensory-neural HL: BC appears better than AC ≫ false Rinnè negative, because the patient does not hear AC and BC sounds by the diseased ear, but in BC testing on this diseased ear, sound is transmitted across the skull to be heard by the healthy ear.

Weber's Test:

Principle:

• It compares hearing by bone conduction in the two ears. It is useful in case of unilateral hearing loss.

Method:

• First, the two ears are compared in the air conduction by Rinnè test. The base of the vibrating tuning fork is placed on the midline of the forehead or on the upper incisor teeth.

Results:

• Normal hearing: sound is heard in midline or equal in both ears.

• Conductive HL: Sound is heard better in (lateralized to) the diseased ear (or the ear with more conductive HL), because the background noise masks hearing in the healthy or better other ear.

• Sensory-neural HL: Sound is heard better in (lateralized to) the healthy or better ear because it has a better inner ear function.

Schwabach's Test:

Principle:

• It compares hearing by bone conduction of the patient with that of the examiner, provided that he has normal hearing.
• It is good for otosclerosis clinical diagnosis.

Method:

• The base of the vibrating tuning fork is placed on the mastoid process of the patient. When the patient no longer hears the tone≫ the tuning fork is immediately transferred to the mastoid process of the examiner.

Results:

• Normal hearing: The hearing duration of the patient and examiner are equal≫ Schwabach normal.

• Conductive HL: The tone is heard longer by the patient ≫ Schwabach prolonged.

• Sensory-neural HL: The tone is heard longer by the examiner ≫Schwabach shortened.

3. Eustachian Tube Function Tests:

Valsalva’s Maneuver:

Forced expiration with both the mouth and nose closed ≫ Increased air pressure in nasopharynx ≫ opening of the Eustachian tube. When the Eustachian tube is patent ≫ the tympanic membrane bulges laterally.

Toynbee test

Otoscopy is done while the patient is swallowing. In normal ET functions, the drum can be seen moving due to opening of ET and passage of air to the middle ear.

Category: ENT Notes