If you’re a client at our practice, you’ve probably heard the word “tympanometry”, whether during your child’s initial evaluation or in subsequent sessions. Below is an outline of what it is, what it means and why it’s important!
The ear is more complex than it looks! The ear is broken up into three main parts—the outer ear, the middle ear and the inner ear. Each part of the ear is crucial to hearing and if any one part is unable to do it’s a job, the entire system can be affected. Sound waves make their way into the outer ear and travel to the tympanic membrane, or eardrum, where they vibrate along three small bones, or ossicles, until they reach the inner ear portion. The vibrations change to electrical signals and the signals are sent to the brain through the hearing nerve. When we do tympanometry testing, we are focused on the middle ear portion of the ear!
Tympanometry testing is used to assess the functioning of the middle ear, or eardrum. The clinician will place a small probe in the individual’s ear until an air-tight seal is created. The reading can only be done if the client is completely still. Luckily, it only takes a couple of seconds to get a reading! The clinician will then obtain a reading in the form of a chart. A number of factors, such as a middle ear infection, a tear in the tympanic membrane (eardrum), fluid in the middle ear, a cold, or any problems with the Eustachian tube can influence a tympanometry reading. There are a number of results, which are presented below.
Type A: This is considered a normal result and indicates middle ear pressure that is within normal limits. This means that the tympanic membrane, or eardrum, is moving normally, there is normal pressure in the middle ear, the ossicles are moving adequately and there is no fluid in the middle ear. If we obtain this reading, there is no need to refer out for a full audiological evaluation.
Type As: This reading can be the result of stiffness in the ossicles in the middle ear. The three tiny bones in our middle ear help to transmit sound, but when they do not move freely, hearing loss can occur.
Type Ad: This reading usually indicates that the ossicles in the middle ear are moving too much and are considered “hyper-mobile”. This could be indicative of ossicular discontinuity or alternatively, a healed tympanic membrane perforation.
Type B: These tympanograms can sometimes be described as “flat”. A Type B tympanogram can mean that there is middle ear effusion or a tympanic membrane perforation. This reading can also indicate that the probe is blocked by cerumen (ear wax), or is against the ear canal, instead of the tympanic membrane.
Type C: A Type C tympanogram can indicate Eustachian tube dysfunction, fluid and air in the middle ear. This reading can result from congestion as well as the tail-end of a cold or ear infection.
If your child is hesitant to allow a probe in the ear, the clinician will try to build rapport and model how the test on done on a doll or stuffed animal. If abnormal results are found, the treating clinician will usually retest 1-2 times. If results continue to be abnormal, the clinician will then refer the client out for a full audiological evaluation.
Jerger, J.F. (1970). Clinical experience with impedence audiometry. Archives of Otolaryngology, 92, 311-324.