How Hearing is Tested
Otoscopy: An otoscope is an instrument used to look into the ear canal. It is important to make sure there is no wax or infection in the ear canal before testing hearing and that the tympanic membrane, or ear drum, is healthy.
Tympanometry: Method of measuring the movement of the tympanic membrane, or eardrum. A machine generates a sound in the ear canal and gives a puff of air which allows the machine to measure how much sound is reflected back. This tells us if the ear drum functions normally as well as the status of the middle ear. It momentarily gives the patient the sensation of being in an airplane.
Acoustic Reflexes: A loud sound is presented into the ear and travels up to the brainstem. A signal is sent from the brainstem down the facial nerve into the middle ear that flexes the stapedius and tensor tympani muscles, which cause the eardrum to tense. This allows the audiologist to make sure this happens when loud sounds enter the ear. If it does not, that may indicate an abnormal function in the ear or facial nerve.
Distortion Product Otoacoustic Emissions (DPOAE): This test uses a machine to determine function of the cochlea, or hearing organ, specifically outer hair cell status. The outer hair cells send the message of sound to the auditory nerve. While they do this they produce a low intensity sound. This machine measures the sound emitted in response to two simultaneous tones.
Pure-Tone Air Conduction Audiometry: A headset is placed over the outer ear or squishy earplugs are placed directly into the ear canal. A pure tone signal is presented into the ear canal and the patient is asked to respond to the sound as it is presented. An audiologist determines the softest level the patient has responded to different frequencies, or pitches, and charts them on a graph called an audiogram. An audiologist interprets the results.
Pure-Tone Bone Conduction Audiometry: This testing is able to measure the hearing sensitivity from the cochlea, or hearing organ, to the brain but excludes the outer and middle ear. A small vibration unit attached to a headband is placed on the bone behind the ear and a tone is presented. The patient is asked to respond to the sound and an audiologist determines the softest level the patient was able to hear the tone. This allowed the audiologist to determine if the outer ear, ear drum or middle ear is causing any hearing loss.
Speech Discrimination: This testing reveals information about how the brain is interpreting the information from the ear. The patient repeats words at a volume based on the hearing test results and comfort. This score tells the audiologist how well the patient understands in quiet and helps them discuss realistic expectations and coping strategies with patients and families.
Auditory Brainstem Response (ABR): The patient listens to clicking or tones under a headset or inserts. Electrodes are used to measure the electrical impulses from the sound in the body up to the brain. Waveforms are produced which can be analyzed by an audiologist to help figure out a persons’ hearing sensitivity.