Before beginning audiometric testing, the audiology clinician will look into your ear canals with an otoscope (an instrument used to direct light into your ear canal). The clinician will be looking at the condition of the ear canal and eardrum. The clinician will also note the amount of earwax and/or anything unusual in the ear canal.
Pure Tone Audiometry
Pure tone audiometry is administered while you are seated in a sound isolated booth. During this test, the clinician uses an audiometer to generate auditory signals of different pitches (frequencies) or "pure tones". The test signal can be presented through earphones; through a small vibrator, which delivers the tones through the vibration of the skull; or through loud speakers. You will be asked to respond each time you hear the tone by pushing a button or raising your hand. The responses are called thresholds and represent the levels at which tones are barely audible. These thresholds are recorded on an audiogram, which indicates the softest level you hear each pitch for each ear. Results of pure tone audiometry indicate the presence or absence of hearing loss, the type of hearing loss, and the degree of hearing loss.
Speech audiometry includes speech recognition thresholds, word recognition testing, and sensitized speech testing (filtered, compressed, speech in noise, etc.). Speech recognition thresholds are determined for each ear and represent the lowest hearing level at which speech can barely be understood. Word recognition testing measures how well the individual understands speech stimuli. Speech audiometry is used for the evaluation of a) hearing sensitivity, b) speech perception ability and c) site of lesion testing.
Another important part of audiological assessment is tympanometry, which measures the mobility of the eardrum. The clinician will place a soft rubber tip in your ear canal, which must fit snugly in order to begin the test. You will hear a buzzing sound and feel some pressure changes in your ear. By recording the response of the eardrum to the changes in air pressure, the audiologist can determine if the eardrum is moving normally. Abnormal eardrum movement may affect hearing ability.
Acoustic Reflex Testing
Acoustic reflex testing is completed for each ear following tympanometry. The acoustic reflex is an involuntary contraction of the muscle attached to one of the small bones behind the eardrum.
During this test you will hear a series of loud sounds of varying pitches in each ear. The equipment measures the presence or absence of the reflex. Acoustic reflex test results provide valuable information regarding the type and severity of your hearing loss and the possible cause of your hearing loss. It is also an important test in detecting problems in the auditory pathway.
Otoacoustic Emissions Testing
Otoacoustic emissions (OAEs) are sounds produced by the cochlea (inner ear) either spontaneously or in response to sound. During this test, a soft tip is placed in your ear canal and you will hear a series of sounds. Results of this testing can indicate presence or absence of hearing loss and the type of hearing loss. In addition, presence of OAEs tends to rule out any abnormality in the conductive pathway (i.e. middle ear). OAEs is a non-invasive objective test, which contributes to the detailed assessment of the auditory system.
Auditory Evoked Potentials
Hearing involves not only the ear, but also the brain. When a sound is heard, we expect some change in the electrical activity of the brain. These minute voltage variations in response to sounds are called AUDITORY EVOKED POTENTIALS. Auditory evoked potentials which occur in the first ten milliseconds after the presentation of a sound originate in the part of the brain called the brainstem and are called the AUDITORY BRAINSTEM RESPONSE(ABR).
The ABR is recorded from scalp electrodes placed on the head, forehead, and earlobes or mastoids. Each ear is tested separately with an earphone. The patient does not respond to the sounds and can even sleep during the test. Sounds called "clicks" are presented at various loudness levels and at different rates. The responses from the inner ear and brainstem, which are detected by the electrodes, are amplified, averaged, and stored in the computer.
The ABR is a non-invasive, objective test, which can be used as an estimate of hearing loss or for assessment of neurological function. ABR can also assess the functional integrity of the central auditory pathway, and can detect abnormalities, such as acoustic tumors.
Auditory Processing Disorders Evaluation
Auditory processing can be defined as "what we do with what we hear" (Katz). It involves various steps or processes that occur, as the auditory signal travels from the inner ear through the central nervous system to the brain. Assessment of auditory processing disorders includes a battery of behavioral and electrophysiological tests in order to evaluate a wide variety of skills. AP testing may be appropriate when the individual is experiencing academic or communication difficulties involving attention, understanding speech, comprehension, memory, or listening in noise.
Last Updated: September 15, 2015