Tympanometry & Acoustic Reflex Testing
Tympanometry
Another important part of audiological assessment is tympanometry which measures the mobility of the eardrum. The vibration of the eardrum is essential in order to hear within normal limits and measuring the mobility of both eardrums will give important information regarding the cause of any hearing loss detected. Before beginning tympanometry, the audiologist will look into your ear canals with an otoscope (an instrument used to direct light into your ear canal). The audiologist will be looking at the condition of the ear canal and eardrum. The clinician will also note the amount of earwax in the ear canal and/or anything unusual in the canal (bean, pencil eraser). Next you will be given instructions, which will include what you will experience during the test and what you need to do during the test. The clinician will place a soft rubber tip in your ear canal and it must fit quite snugly in order to begin the test. You will hear a buzzing sound and feel some rapid but mild pressure changes in your ear. It is important not to talk, swallow or move your mouth or head, during this test however the actual test only takes a few seconds. By recording the response of the eardrum to the changes in air pressure, the audiologist will know if the eardrum is moving normally. If abnormal eardrum movement is noted and this abnormality is affecting hearing ability, a patient will be referred to a physician. Usually with pharmacological or surgical intervention, any hearing loss caused by abnormal eardrum movement can be corrected.
Acoustic Reflex Testing
Acoustic reflex testing is completed with the same equipment used during tympanometry. Acoustic reflex testing is done in each ear following tympanometry. You may remember from previous science classes that the tiny air filled space beyond the eardrum houses the three smallest bones in your body. These tiny bones help to transfer the sound, which has vibrated the eardrum, into the cochlea where the hearing nerves are located. Connected to the tiniest of these bones is a muscle which contracts involuntarily when loud sounds or noises are heard. This muscle contraction is called an acoustic reflex, and the lowest level that it occurs is called an acoustic reflex threshold.
During this test you will hear a series of loud sounds of varying pitches in each ear. You do not need to tell the audiologist you have heard the sounds as the equipment will measure the presence or absence of the reflex. It is important that you sit very still during this testing and not move your head or mouth. The complete acoustic reflex test battery takes only a few minutes.
Acoustic reflex test results give the clinician valuable information regarding the severity of your hearing loss and the possible cause of your hearing loss. It is also a valuable test in detecting problems in the auditory pathway.