Audiology – is derived from a Latin word called audīre, means “to hear”, is the branch of science that studies hearing, balance, and related disorders.
Audiology aims to determine whether someone can hear within the normal range, and if not, which portions of hearing (high, middle, or low frequencies) are affected and to what degree. Audiologists are experts in the management of the auditory and balance systems.
There are number of tests available to determine the degree and type of hearing loss e.g. PTA, Impedance, OAE, BERA, ASSR etc. Once the diagnosis is confirmed with these test the patient is referred to the ENT Specialist for management of the hearing loss.
It is important to remember that these tests are ‘Non Invasive’ and do not cause any pain!
Pure Tone Audiometry (PTA)
Pure tone audiometry is a hearing test used to determine the presence or absence of hearing loss and also the type and severity of hearing loss. This test involves placing earphones on both ears and pressing a button or raising your hand when you hear a sound.
Speech audiometry is a test using words to determine how softly words can be heard and how clearly words are understood. You will listen to a list of words and repeat them back to the Audiologist. The words lists are presented at different intensities. The results of word understanding are measured by a percentage score. The main purpose of this test is to check the ability to recognise speech.
These tests assess the function of the eardrum and middle ear structures. Immittance tests involve placing a plastic tip in the ear canal which measures changes in air pressure. These non-invasive tests can be completed in 10 minutes.
Tympanometry – assists in the detection of fluid in the middle ear, perforation of the eardrum, or wax blocking the ear canal. Tympanometry pushes air pressure into the ear canal, making the eardrum move back and forth. The test measures the mobility of the eardrum. Graphs are created, called tympanograms. These can reveal a stiff eardrum, a hole in the eardrum, or an eardrum that moves too much.
Acoustic reflex – measures add information about the possible location of the hearing problem. Everyone has an acoustic reflex to sounds. A tiny muscle in the middle ear contracts when a loud sound occurs. The loudness level at which the acoustic reflex occurs—or the absence of the acoustic reflex—gives information to the audiologist about the type of hearing loss.
Static acoustic impedance – measures the physical volume of air in the ear canal. This test is useful in identifying a perforated eardrum or checking the openness of ventilation tubes.
Otoacoustic Emission (OAE) Testing
The otoacoustic emissions (OAE) test that check the outer hair cell function of the inner ear(cochlea) to estimate hearing sensitivity. It is now used as a new born screening test.
The ABR test The ABR test is used to test the functional status of the auditory neural pathway (how sounds travel to the brain) and to assess hearing when behavioural testing cannot be performed due to age, cooperation, or developmental level.
Test Procedure :
The ABR test is performed on an individual who is resting quietly or in a sleep state. Mild sedation may be used, when necessary, under a physician’s supervision. A series of clicks are presented to each ear through special earpieces inserted into the ear canals. The audiologist can vary the intensity of the clicks. The individual wears a headband which records appropriate brain wave activity. The averaging computer in the ABR unit then analyzes the information and it is compared to normal responses. This procedure does not cause any discomfort to the person. The test takes approximately one to two hours.
as a screening procedure for newborns who are at risk for hearing loss.
as a diagnostic tool to identify infants and small children with a hearing loss.
to estimate hearing levels in difficult to test patients, i.e., mentally retarded, autistic, developmentally delayed.
Caloric test -
This is a balance test that checks the balance function arising from the vestibular system. During this test,you will be stimulated to feel dizzy while lying down. Warm and cool water sequentially irrigated into the ear canals with rest breaks in between each irrigation. You will feel dizzy for about 2 minutes in a controlled fashion and you should not feel dizzy once the test has been completed. Duration of this test is one hour.