A Hearing Evaluation is a battery of tests in order to assess the lowest level the patient is able to hear across the frequencies of sound. There are other tests in the battery to assess the health of the middle ear and the inner ear and further pathways to the brain.
• Comprehensive Audiometry: is a battery of tests to assess two aspects of hearing.
Sensitivity is the patient’s ability to hear soft sounds. The tests to measure sensitivity use words and pure tones presented to the patient through ear inserts and a bone vibrator that are connected to an audiometer
Speech Discrimination is the patient’s ability to tell the difference between speech sounds while listening to multiple words at a comfortable level. These are presented to the patient in the same manner as above.
• Tympanometry: is the measurement of how much sound is able to pass through the middle ear. A probe is placed in the ear, sealing it off from the environment. A subtle tone is presented in the ear and measured through a microphone in the probe. The air pressure is gently adjusted in the ear canal and the machine measures how much sound has made it through the middle ear based on the pressure. This test is very quick and painless, and is important in determining the health of the middle ear. If the eardrum does not pass very much sound due to middle ear fluid or the absence of an eardrum, some hearing loss may be present.
• Acoustic Reflex Testing: Measures the presence of a reflex of a middle ear muscle during a loud sound. This test is performed with the same equipment as tympanometry above. An airtight seal is formed with the gentle tone present in the ear. A somewhat loud tone is presented and the sensitive equipment measures the passage of sound. If it changes in response to the loud sound, an acoustic reflex is present. This test measures the health of the 7th and 8th cranial nerves.
• Otoacoustic Emissions Testing (OAE): Measures the presence of sounds in the inner ear that are a by- product of a healthy ear. This test is performed much in the same way as the above tests with a probe in the ear. Two tones are presented to the patient and a microphone in the probe records the expected presence of the sound per specific frequency. These tests are important in the evaluation of children and newborns as well as monitoring noise induced and medication induced hearing loss. If there is an OAE present, then the results rule out anything worse than a mild hearing loss.
• Auditory Brainstem Response (ABR): Measures electrical signals that occur in the brainstem while the patient hears moderately loud clicks. This test is performed with very sensitive equipment that is designed to measure the brainstem’s electrical activity as sound is sent to the brain. Electrodes are placed on the patient’s forehead and behind the ears and the test is performed in a quiet room. This test rules out a very specific type of hearing loss.