A comprehensive audiology evaluation consists of a series of individual diagnostic tests that measure different aspects of your hearing. Following a physical examination and a review of your medical history, you will be given any or all of the following tests:
Pure Tone Audiometry
Pure Tone Audiometry is a behavioral test used to determine hearing sensitivity.
The patient is seated in a sound-treated room. Foam inserts or headphones are placed and the patient is asked to press a buzzer each time a sound is heard. The softest sound the patient can hear, called a threshold, is plotted on a graph called an audiogram. Thresholds are recorded for low (250 Hz) to high (8000 Hz) frequencies (pitch), for each ear individually. The audiogram shows whether the patient has hearing loss and to what degree.
If a hearing loss is diagnosed, it’s important to determine whether the loss is caused by a medical condition in the outer or middle ear that may be medically or surgically treatable. This type of hearing loss is called conductive. If the loss is caused by damage in the inner ear, the hearing loss is most likely permanent. This type of permanent hearing loss is called sensorineural.
This distinction between these two types of hearing loss is made using a bone oscillator, which sends vibratory signals directly to the inner ear, bypassing the outer parts of the ear. If hearing thresholds are better with bone conduction than through air conduction (inserts or headphones), this suggests a conductive hearing loss. When bone conduction thresholds are approximately equal to air conduction thresholds, this suggests a sensorineural hearing loss.
A hearing loss with both sensorineural and conductive components is called a mixed hearing loss.
Speech Audiometry is a measurement of speech reception and discrimination abilities.
The patient is already seated for the pure tone audiometry portion of the hearing test. Through the inserted earphones or headphones, the patient will hear words descending in loudness and is asked to repeat each word or take a guess if the word is hard to recognize.
The lowest level at which the patient can repeat the correct word two out of three times is called a speech recognition threshold. This threshold is recorded for each ear individually.
Once the speech recognition threshold is recorded for each ear, the audiologist will present a list of recorded words at a louder presentation level, depending on the patient’s degree of hearing loss, configuration and sensitivity to loud sounds. The patient is asked to repeat back each word, taking a guess even if the word is hard to understand.
This test is more difficult, as it assesses the patient’s ability to understand single-syllable words with no contextual or visual cues.
Tympanometry is an objective test used to measure middle ear function.
The patient is seated and a small rubber tip is placed at the entrance of the ear canal. The patient may hear a low buzzing sound and feel a change in pressure. If a tight ear seal can be obtained, the tympanogram will give the audiologist information about the volume of the ear canal, the resting pressure of the eardrum and the stiffness (or compliance) of the eardrum.
Tympanometry is helpful in determining whether the eardrum is moving sufficiently. If there is fluid behind the eardrum, Eustachian Tube dysfunction or a disarticulated ossicular chain (damage to the middle ear bones), the tympanogram may show an abnormal result. If the patient has a pressure equalization tube (PE tube), a tympanogram will show if the tube is open or clogged.
Acoustic Reflex Testing
Acoustic Reflex Testing is an objective test used to measure a reflexive response to intense sound in the middle ear.
This test is usually completed at the same time the tympanogram is measured, as long as a good ear seal can be obtained. The patient is asked to sit quietly. Loud sounds are delivered to the ear canal and the reflex is observed. The threshold of the observed reflex is recorded for different frequencies (pitch).
This result is useful in checking consistency of hearing test results, especially in situations where the reliability of patient responses is questionable. This test can also provide insight into patients with central nervous system dysfunction.
Otoacoustic Emissions Evaluation
Otoacoustic Emissions Evaluation is an objective test used to measure inner ear hair cell function.
There are two types of otoacoustic emissions used clinically: Transient-Evoked otoacoustic emissions (TEOAE) and Distortion-Product otoacoustic emissions (DPOAE). Both are used to verify results of the hearing test.
The patient is seated and asked to remain very quiet and still. A series of sounds are presented to the ear through a small probe that fits inside the ear canal. The probe contains a tiny loudspeaker that generates the sounds and a microphone picks up an “echo” that is produced by the inner ear in response to those sounds.
Otoacoustic emissions, coupled with tympanometry, can be useful in evaluating whether the ear is clear and functioning for infants and young children. Even if behavioral measurements are unable to be obtained, these tests can give the audiologist and physician a good indication of whether the child has the ability to hear.
Call Texas ENT & Allergy at (979) 693-7419 for more information or to schedule an appointment.