Audiological adventures · 5 February 07
Audiogram (hearing test)
The objective of a hearing test is to measure your threshold for hearing tones and speech. During the hearing test, the Audiologist will use headphones that most often look like something you would find in an old German u-boat.
When the test starts, you will be instructed to respond each time you hear a soft tone presented in either ear. In addition, you may occasionally hear a static noise in the background (masking noise) that should be ignored. The Audiologist will measure your threshold for tones over a range of frequencies (typically, the range is 250 to 8000 Hz – the frequency range necessary to understand speech).
Speech Testing is used to measure the lowest level at which you can repeat two-syllable words and also your ability to understand and repeat single-syllable words presented at a loud volume.
Electronystagmogram (ENG)
The most common audiological test ordered for individuals complaining of dizziness or vertigo. This test records and measures voluntary and involuntary eye movements, specifically nystagmus (the involuntary back and forth jerking movement of the eyes that occurs when the entire balance system is stimulated).
The ENG is comprised of a series of subtests:
- Oculomotor Analysis – patients perform various visual tasks that involve watching a little projected square dart around a wall
- Positional Testing – patients are placed in various body positions to determine if dizziness develops and to see if nystagmus occurs
- Caloric Stimulation – small amounts of both warm and cool water are introduced into each ear canal to independently stimulate the inner ear vestibular system
The patient wear goggles housing special video cameras that track eye movement that is reported to and recorded by a computer.
Auditory Brainstem Response (ABR)
This test is performed on an individual who is resting quietly. 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 electrodes on their head which record appropriate brainwave activity. The averaging computer in the ABR unit then analyzes the information and it is compared to normal responses. If the results of the test suggest some degree of hearing loss, you may be referred for further testing.
Electrocochleography (ECoG)
This test is an objective measure of the electrical potentials generated in the inner ear as a result of sound stimulation. This test is most often used to determine if the inner ear (cochlea) has an excessive amount of fluid pressure which can cause symptoms such as hearing loss, aural fullness, dizziness, and/or tinnitus.
A patient undergoing an Ecochg test will have several surface electrodes placed on their head. A tiny microphone and an earphone will then be inserted into the canal of the test ear. The patient will be instructed to relax while they listen to a clicking sound. No response from the patient is required for this test.
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