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Voice tests and tuning fork tests are easily carried out in a doctor’s office with little or no equipment.
A good idea of how well a patient hears can be established through simple observation – can he/she hear normal conversational voice or do you have to raise your voice to make yourself clear? If a patient is deaf, you need to know roughly how much and what type (conductive, sensorineural or mixed) of hearing loss he/she has. Simple voice/whisper tests can be conducted for a crude assessment of hearing level.
Tuning fork tests
Tuning fork tests can help with lateralising deafness and with deciding which type of hearing loss is present.
TIPS FOR TUNING FORK TESTS
Pure Tone Audiometry
Voice tests and tuning fork tests are helpful, but fairly crude. Formal testing is required for an accurate assessment of hearing levels. For adults and older children who can co-operate (age 4 years upwards), this is best done by pure tone audiometry (PTA).
Evoked Response Audiometry
PTA needs the patient’s co-operation and is therefore a subjective test. To test the hearing objectively a stimulus is presented to the ear and the resultant changes in electrical activity in the nervous system can be measured. These techniques, evoked or electrical response audiometry (ERA), are widely used in children and in disputed cases in adults.
Electrical signals are generated by the normal inner ear in response to a sound. These are referred to as ‘otoacoustic emissions’ (OAE) and are used as a screening test for hearing in newborn children. OAEs will be absent if the child is deaf.
Hearing tests in children
PTA can be very difficult in young children (under 4 years) or in older children and adults with learning difficulties. A skilled tester can use various behavioural audiometry techniques to obtain an accurate assessment of the child’s hearing.
Tympanometry relies on a device that puffs a small current of air into the ear and measures the degree of ‘distensibility’ of the eardrum and middle ear. A normal trace with a peak suggests that the drum is intact and there is air under normal pressure. A ‘flat’ tympanogram is typical of a middle ear effusion/glue ear.