06 Jul Audiometry: The Who, What, Why and How of Hearing Test
Audiometry is a hearing test audiologists use to examine your natural hearing ability. They test issues related to the inner ear, such as hearing certain tones and balance.
We have highlighted the different types of audiometry exams that a hearing health professional may conduct when working with a patient.
The Different Types of Audiometry
Pure – Tone Audiometry (Air Conduction Test): This is the most common hearing test. With a pair of headphones, sounds go through your outer and middle ear to assess the auditory sensitivity.
Bone Conduction Audiometry: Similar to the pure-tone audiometry test, but instead of headphones, a small device is placed behind the ear or on the forehead. Gentle vibrations are sent through the bone to the inner ear to determine how well you hear. It also tells you if there is a problem in your outer or middle ear.
Speech Audiometry: This test helps identify neural types of hearing loss. The auditory system is assessed by evaluating the hearing ability. An audiologist talks through a pair of headphones and the listener has to repeat them.
Suprathreshold Audiometry: Similar to speech audiometry, this is a speech recognition test. This helps detect the different degrees of hearing loss in both ears by testing whether the listener can accurately recognize the speech at a typical conversational speech level.
Self – Recording Audiometry (Bekesy Audiometry): This is where the listener gets to control the increase and decrease of the intensity as the frequency is gradually changed back and forth across the threshold of hearing.
Impedance Audiometry: The measurement of mobility and air pressure of the middle ear system and its reflexes is tested.
Computer – Administered (Microprocessor) Audiometry: An advanced version of the self-recording audiometry.
Subjective Audiometry: Listeners respond to various sound stimuli.
Objective Audiometry: This test helps identify if there is any damage in the inner ear. The listener does not need to respond, thus this is typically performed on newborns and infants.
Electrocochleography (ECog): Measures the electrical activity in the inner ear, generated by the cochlea and vestibulocochlear nerve in response to sound.
Auditory Brainstem Response (ABR) / Auditory Evoked Potential (AEP): This test checks the hearing nerves and hearing center in the brain and how well they function. This determines if you have sensorineural hearing loss. Electrodes are placed on your head and connected to a computer. With the use of headphones, your responses to the sounds you hear are recorded by your brain wave activity.
Electronystagmography (ENG): The brain and the inner ear are connected by the acoustic nerves, which controls hearing and balance. This is a balance test (there are four different ways to test this) and is the most common test performed on detecting Meniere’s disease.
Tympanometry: This test measures the movement in the eardrum caused by air pressure. This helps determine if there is excess fluid, a buildup of wax, eardrum perforations, or tumors. A small probe that looks like an earphone is placed into each ear. Air is pushed into your ear and is recorded onto a graph. The shape of the graph shows the movement of your eardrum. It identifies if your eardrum moves in the correct way, if it is too stiff, if it moves too much, or if it has a hole in it. It can also help find out if a child has an ear infection.
Acoustic Reflex Measures: A similar test to tympanometry. Here, your reflexes to sounds are recorded. This is done by entering a probe into your ear and a tiny muscle in the middle ear will tighten as sound comes through.
Static Acoustic Impedance: The air in the ear canal is measured to show if there is a hole in the eardrum, if your tubes are open or blocked, and if there is fluid behind your eardrum.
Otoacoustic Emissions (OAEs): This is where sounds produced in the inner ear are detected. The vibrations from the inner ear produce a very quiet sound that echoes back into the middle ear, which is how we measure OAEs. However, hearing loss greater than 25-30 decibels (dB0) will not be able to produce these soft sounds. This test is done with earphones that emit sounds and measures the sound that comes back. This helps determine if there is a blockage in the ear canal, a buildup of fluid in the middle ear, or if there is damage to the cochlear hair cells.