Tympanometry is a critical tool for diagnosing and evaluating middle ear function. In this article, we will explore what tympanometry is, break down the various types of tympanograms, guide you on how to interpret tympanometry test results, and clarify the significant distinctions between clinical and portable tympanometers.
Tympanometry is a non-invasive audiological test used to evaluate the health and functionality of the middle ear. It provides valuable insights into the condition of the eardrum (tympanic membrane) and the middle ear, specifically the mobility of the ossicular chain (tiny bones in the middle ear) and the presence of any fluid, eardrum perforations or blockages.
Tympanometry involves the application of both negative and positive pressure to the middle ear while maintaining a constant probe tone. Through tympanometry, hearing care professionals evaluate the absorption and reflection of the probe tone within the middle and inner ear. This assessment enables clinicians to gain insights into the behavior and functionality of the middle ear system (tympanic membrane, ossicular chain and eustachian tube).
A tympanometry test is a non-invasive assessment of the compliance of the middle ear, i.e., its ability to transmit sound effectively. It measures the impedance of the middle ear by varying the air pressure within the ear canal and recording the corresponding changes in the eardrum’s movement.
The tester inserts a small probe into the ear canal during a typical tympanometry test. The probe consists of a speaker and a microphone (and an air pressure tube). The speaker emits a pure tone sound, which travels into the ear canal, while the microphone measures the sound reflected back. The air pressure tube is connected to a pump that systematically varies the air pressure in the ear canal, recording the amount of reflected sound as the air pressure changes.
A tympanogram is a graphical representation generated through tympanometry, typically displaying the motion of the tympanic membrane. It commonly takes on a pyramid-like shape. The highest point on a tympanogram corresponds to when the eardrum experiences equilibrium between negative and positive pressure. With a classification framework like Jerger’s template, it becomes feasible to ascertain whether the tympanic membrane exhibits unrestricted movement or if there is an underlying disorder.
Tympanometry results are typically represented on a graph, known as a tympanogram. The chart displays compliance (y-axis) to air pressure (x-axis). By analyzing the shape and position of the tympanogram, hearing care professionals can make informed assessments about the middle ear’s functionality. Here are the primary tympanometry types, as purposed by Jerger:
Figure 1. Tympanogram Type A
Figure 2. Tympanogram Type As
Figure 3. Tympanogram Type Ad
Figure 4. Tympanogram Type B
Figure 5. Tympanogram Type C
Figure 6. Tympanogram for Ear Drum Perforation
Figure 7. Tympanogram types as purposed by Jerger
Tympanometry testing involves using a tympanometer. To conduct the test, a probe is carefully placed into the ear canal, ensuring an airtight seal. Subsequently, the probe administers varying levels of air pressure within the ear canal while simultaneously tracking alterations in the impedance of the middle ear. The collected data is then charted on a tympanogram graph, serving as a valuable source of information for audiologists.
Figure 8: The basic components of a tympanometer. The loudspeaker introduces a 226-Hz tone to the ear canal while the pump varies the air pressure above and below atmospheric pressure in the ear canal. The microphone records the level of the tone at various ear canal pressures.
Tympanometers come in two primary forms: clinical/ diagnostic and portable/ screening. Each has its own set of advantages and applications:
In summary, tympanometry is a vital tool in diagnosing and assessing middle ear function. Understanding the distinct types of tympanometry, reading tympanometry test results, and distinguishing between clinical and portable tympanometers can help hearing care professionals effectively monitor and manage ear health.
Are you considering purchasing a clinical or screening tympanometer? Explore our wide selection here.
Other Good Reads: The Benefits of Wide Band Tympanometry
