MANUAL PHYSIOLOGY PRACTICAL - Repository:The Medical ...

FM/UOJ
Experiment 3
TESTS FOR HEARING
Hearing includes perception of sound waves in terms of pitch, amplitude and
amber, higher functions such as recognizing and understanding the meaning of the words
and the source of sound. This practical demonstrates the tests for perception of sounds
only.
The receptors are in the internal ear and different areas in the basilar membrane
respond to different frequencies. When sound waves reach the ear, they vibrate the
tympanic membrane, which is amplified by the ossicles and transmitted to the fluid in the
inner ear where appropriate receptors are stimulated: air conduction. Any vibration that
travels through the bones of the skull will also be transmitted to the bony covering of the
inner ear and to the fluid in it and stimulate the receptors: bone conduction. When there is
defect in the external or middle ear, the air conduction is defective but hearing is possible
through bone conduction. In defects of inner ear, hearings by both conductions fail.
Clinical Examination:
A simple clinical examination for hearing is to cover one ear and speak to the
subject from behind (to avoid lip-reading) in low voice. Then repeat the same for the
other ear.
Tuning fork test:
Tuning forks of different frequencies are used to test the whole hearing range of
frequencies. Two different types of tests are available to test for hearing loss and to
differentiate the conduction deafness from nerve deafness.
Rinne’s test:
Strike a tuning fork and place its base on the mastoid process and ask the patient
whether the sound is heard. If it is not heard, strike hard and repeat it. If it is not heard the
subject is likely to have nerve deafness for that frequency. If it is heard hold it until the
sound disappears. As soon as the subject indicates the disappearance of the sound hold
the top of the tuning fork near the external auditory meatus. If the subject hears the sound,
the ear is probably normal and if not the subject probably has conduction deafness.
Repeat the test for that ear with tuning forks of varying frequencies to cover the audible
range. Then test the other ear.
Weber’s Test:
Strike a tuning fork and place its base on the vertex or at the centre of the
forehead. Ask the subject whether the sound is heard in both ears equally or which ear is
louder. If both ears are similar the hearing is normal. If one ear is louder than the other,
the louder ear may have conduction deafness or the other ear may have partial or
complete nervous deafness.
Neurology
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