Hearing tests are important in the diagnosis of diseases of the ear. There are a wide range of hearing tests and each gives information on different subjects. Otolaryngologist will decide which one to be conducted according to the patient's complaints, examination findings and the results of other diagnostic tests.
Pure tone audiometry
It is the most common ear test. It determines the least sound intensity that could be heard by both ears at different frequencies (thin and deep sound). The patient is asked to sit in a soundproof booth. The sound is given to the patient's ear through a headset. When he hears the sound, he presses the button to confirm it. Thus, the sound level he can hear is determined.
In this measurement, air and bone conduction hearing levels are established. Air conduction measurements give information about hearing paths from earlap to the brain. Bone conduction measurements give information as from inner ear.
The source of hearing loss can also be identified by looking at air and bone conduction measurements.
Tympanometry
It is a test for measuring pressure in the middle ear.
It is very easy to apply. Pressure in the middle ear is measured by a prob inserted into external ear canal. As a result, a graph and a pressure value are obtained. Decline in pressure is seen in middle ear infections and adenoid or allergy-induced pressure problems, especially common in children.
Stapes Reflex
Stapes is the name given to the stirrup bone in the middle ear. Stapes reflex is the reflex created by the movement of stirrup bone in the middle ear to an audible impulse. Creation of this reflex is caused by auditory nerve and the facial nerve. When a sound is given to one ear, stapes in both ears move.
Measurement is made by a tool called tympanometer. A probe is attached to the patient's ear. When the sound is given, stapes' movement is measured through changes in middle ear pressure. Normally, stapes reflex is received. Cases where it cannot be received give us information about certain diseases. It is especially important to detect otosclerosis, a disease of calcification of stapes bone in the middle ear. It also gives information on diseases of facial nerve and the brain stem.
Measurement of Speech Discrimination Ratio
It is a test to measure the percentage of speech which the patient understands. After hearing thresholds are determined, some words are read in the intensity that the patient can hear. A measurement is made according to how many of these words the patient can repeat.
It may be important for especially patients who will be given hearing aids, patients to be operated for chronic otitis media, and in the case of Meniere's disease and Arthritis of the middle ear (otosclerosis ).
SISI
It is applied in the case of diseases related to the inner ear.
A normal ear doesn‘t notice very small increases in sound intensity. However, such increases are noticed in the case of problems related to the inner ear. In other words, by SISI test, the fact that the patient notices such increases may suggest inner ear disease. It is an easy test to apply but it is not a final diagnostic test although it gives an idea to the doctor.
Tone Decay
It is based on the principle that the ear shows adaptation to a sound given in a certain tone. When the sound is given to the patient, after a period of time, the patient becomes unable to hear it. Sound intensity may need to be increased for the patient to hear for a specific period of time.
In the case of diseases related to auditory nerve, adaptation to a sound given at a certain tone develops very fast. Again, it is not a final diagnostic test although it gives an idea.
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