Hearing health professionals perform multiple tests as part of a comprehensive hearing evaluation. The methods used vary based on the age of the person, the environment, and the purpose of the test. Read on to familiarize yourself with what test might be performed at your next hearing appointment. You have one scheduled, right?
Pure Tone Test
The most common is pure-tone testing. Sounds are projected at different tones, intensities, and frequencies. The patient then indicates which sounds they are able to hear. This test can differentiate between one-sided versus bilateral hearing loss.
There are two transducer modes of pure tone testing: air conduction and bone conduction. During an air conduction test the sounds are delivered through a set of head or earphones. Bone conduction is a little different.
Bone Conduction Test
This test uses a device called a bone oscillator. It is a transducer that looks like a small square box attached to the end of a metal headband. The headband is placed over the head with the square box resting on top of the mastoid bone behind the ear.
Again, the test is performed by projecting sound at different tones and frequencies. But this time the sounds will be ‘heard’ through the vibration of the mastoid bone in the skull. By by-passing the outer and middle ear, the test is able to confirm that a hearing impairment is not the result of a conductive blockage. Rather, a sensorineural, or nerve-related, hearing loss is present.
The results of an audiometer pure tone test are recorded on an audiogram. This is a graphical representation of how loud sounds must be before the patient is able to perceive them.
Like pure tone testing, there are various types of speech tests that can be performed as part of a comprehensive hearing evaluation. One can check how loud speech needs to be for it to be detected. Another checks for how well the words can be heard and distinguished at a conversational level.
Speech Reception Threshold (SRT) Test
During this test, the patient is asked to repeat a list of known words presented at different volumes. The test determines the lowest volume at which speech can be heard and recognized. In conjunction with pure tone testing, it validates the patient’s hearing threshold.
Speech Discrimination Test
Hearing loss and speech discrimination often go hand in hand. During this test, the patient listens and then repeats a list of one-syllable words. Results are recorded as a percentage of the number of words correctly repeated back. The test helps to determine an individual’s level of candidacy for hearing amplification. As such, it is often used in the selection and fitting of hearing aids.
Tests of the Middle Ear
The middle ear is integral to hearing. Comprised of 3 tiny bones, membranes, and tubes, it transmits sound from the outer to the inner ear. The three tests used to evaluate the function of the middle ear are:
- Tympanometry (evaluation of the eardrum)
- Acoustic reflex threshold (ART)
- Static acoustic impedance
Using a tympanometer, variations in air pressure are presented to the middle ear. This test helps to determine eardrum mobility, resting middle ear pressure, eardrum compliance, and cumulatively how effective the eardrum is at transmitting sound to the middle ear cavity and therefore the inner ear as well.
Acoustic reflex threshold (ART)
Responding to relatively high-intensity sound, the connective tissue of the middle ear will contract involuntarily. ART measures the sound pressure level that will trigger this reflex and compares it to norms for individuals with hearing within normal limits.
Static acoustic impedance
This is a test to measure air pressure flow in the ear canal. It is used to identify blockages or even a hole in the eardrum. It can also detect if there is fluid behind the eardrum.
Auditory Brainstem Response (ABR) Testing
ABR is a neurologic test of the function of the auditory system through to the brainstem. During a comprehensive hearing evaluation, it is used to measure the hearing nerve’s response to sound. The patient must lie perfectly still. In very young children the test can be performed while they sleep. Three to four electrodes are applied to the patient’s head and in front of their ears. Using a computer, sound is delivered through earphones. The electrodes then measure how the hearing nerve responds to the sound stimuli.
Otoacoustic Emissions Testing (OAE)
This is a test of the inner ear or cochlea. It measures emissions, which are sounds given off by the inner ear in response to sound. When the hair cells of the inner ear vibrate, they produce a quiet response that echoes back into the middle ear. This sound – or OEA – is a measure to help determine if hearing is within normal limits or not.
OAE tests can also help determine if there is a blockage in the outer or inner ear. If there is a blockage, no sound will get through meaning that no vibration or sound will be measurable by the OAE probe.
During a comprehensive hearing evaluation, your hearing health professional will employ one or several of the tests described above. Again, each patient, environment, and reason for the test will determine what combination he or she may perform. Furthermore, there is a variety of equipment that can be used. Having your hearing fully evaluated is important. Did you know that hearing loss is the world’s leading disability? Don’t put it off. Make an appointment today.