An audiologic evaluation is sometimes thought of as "just a hearing test," but much more than "just" hearing beeps is involved! A comprehensive audiologic evaluation consists of a battery of tests to evaluate the function of each specific part of the auditory system. Before appropriate rehabilitation for hearing loss can be determined, the location(s) of the damage causing the hearing loss must be identified. Here is the process from start to finish...
The audiologist will ask numerous questions during the case history to best understand why the patient has come to our office. A thorough history guides the audiologist to determine the most appropriate diagnostic test battery for each patient.
The audiologist will look at the outer ear (the pinna) checking for any malformation. The audiologist will use an otoscope, an instrument that contains a light and a magnifying lens, to examine the ear canal and eardrum for any abnormalities and/or need for a medical referral.
Acoustic immittance measures are a battery of tests including tympanometry and acoustic reflex testing. These tests give diagnostic information to help identify where a problem is occurring in the auditory pathway.
Tympanometry changes air pressure in the ear canal to measure the movement the eardrum to show stiffness, flaccidity, or normal eardrum movement. This test is also useful in identifying a perforated eardrum or the openness of ventilation tubes.
We all have an acoustic reflex to sounds. A tiny muscle in the ear contracts when a loud sound occurs. The audiologist will measure the loudness of sound needed to elicit the acoustic reflex, if the reflex is present.
When sound enters the inner ear, small “hair-like” cells in the normal-hearing portions of the inner ear vibrate. The vibration produces an inaudible sound known as an otoacoustic emission (OAE) that echoes back into the middle ear. The sound can be measured with a small probe in the ear canal. OAEs assist the audiologist in better determining where the problem is occurring in the complex auditory pathway.
Pure-tone audiometry is completed in a sound-treated booth with special treatment to the walls, ceiling, and floor to ensure that background noise does not affect test results. The audiologist uses a calibrated machine called an audiometer to present tones at different frequencies (pitches) and at different intensity (loudness) levels. The patient’s responses are recorded on a chart called an audiogram that provides a graph of intensity levels for each frequency tested.
A pure tone air-conduction hearing test is given to determine the faintest tones a person can hear across a range of pitches (frequencies). During this test, the patient wears earphones and is instructed to respond when a tone is heard. Once the thresholds have been found through air conduction, the same process is repeated for bone conduction. In this test, tones are introduced through a small vibrator placed on the temporal bone behind the ear. This testing can measure functionality of the inner ear independently of the functionality of the outer and middle ears.
By comparing air conduction and bone conduction test results, the audiologist can determine whether there is a hearing loss due to a problem in the outer, middle, and/or inner ear.
Speech audiometry includes determining speech reception threshold (SRT) and testing of word recognition.
Speech reception threshold testing determines the faintest level at which a person can correctly repeat easy-to-distinguish words. A separate SRT is determined for each ear.
Word recognition testing allows the audiologist to determine how well a patient understands words that are presented at a comfortable loudness level. In this test a male-recorded voice asks the patient to repeat words at the same comfortable loudness level throughout. The score is represented in a percentage ranging from a score of 100% (indicate that every word was repeated correctly) to a score of 0% (would suggest no understanding). This testing is extremely valuable when establishing realistic expectations for rehabilitation.
After the test battery is completed, the audiologist will review each component of the audiologic evaluation to obtain a profile of hearing abilities and needs. Additional specialized testing may be indicated and recommended on the initial test results. Audiologic evaluations may result in recommendations for rehabilitation through counseling and/or fitting of appropriate hearing devices or through referrals to appropriate professionals. Our audiologists work as a part of an interdisciplinary team to best serve the individual needs of each patient.
As you can see, an audiologic evaluation is much more than "just a hearing test!"