Tuning fork tests

Tuning fork tests can help with lateralising deafness and with deciding which type of hearing loss is present (Figures 3.1 and 3.2).

•  Use a 512-KHz fork with a good heavy base.

•  If the hearing is equal in both ears, the Weber test will not lateralise to one side (i. e. the patient will hear the sound in the middle).

•  If the Weber is to one side, this can indicate that the other side has little or no hearing, or that there is a conductive deafness on the side the patient identifies as better. Try it yourself - put your finger firmly in the external canal of your own ear and place the tuning fork on your head; you should hear it louder on the side you have blocked as you have given yourself a mild conductive hearing loss.

•  The Rinne test is negative if the patient hears the sound better by bone conduction. Usually this means there is a conductive loss on that side.

•  Be careful interpreting the Rinne test if the patient has profound hearing loss on one side. A Rinne negative may be because he/ she hears sound transmitted across the head from a good ear

- false negative Rinne. Masking of the good ear with a noise box helps overcome this problem.

•  Tuning fork tests are quick and easy but skilled audiometry is essential to assess and classify deafness.

4 years upwards), this is best done by pure tone audiometry (PTA).

PTA is performed in a sound-proofed room. The patient is presented with a series of sounds and indicates when he/she can hear them. Air conduction is tested by sounds fed through a headphone; bone conduction by sounds used to vibrate a probe placed on the mastoid bone. The graph is plotted across different frequencies as in Figure 3.3. This is performed separately for each ear.

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