While a variety of probe tones exist, and yield different results, a 226 Hz tone is most used for patients above 6 months of age. At this frequency, the adult ear (and the ear of older children) is stiffness dominated so the effects of mass and friction can be mitigated.

Infant's ear canals, however, are not fully developed. Specifically, the bony portion of the ear canal is still quite compliant, and thus the system is more mass dominated. Other changes, like the fusion of the tympanic ring, the stiffening of the ossicular chain, and changes in the size and shape of the ear canal affect the response to different frequencies of probe tone. As a result of these differences in infant ear canals, a lower resonant frequency is utilized, making the responses to a higher probe tone more accurate than that of the 226 Hz tone used with adults. Most clinics utilize a 1000 Hz probe tone for infants under 6 months of age, primarily to detect middle ear effusion or fluid in the ear.

Compliance is a measure of ear drum mobility at the point where pressure in the ear canal is equal to that inside the middle ear space. In short, the compliance is visualized on a tympanogram as the height of the vertical peak of the graph. Although a direct measure of tympanic membrane movement, compliance values can provide insight into the function of the entire middle ear system. For example, otosclerosis, which does not affect the ear drum, but the stapes footplate within the middle ear space, would result in a lower-than-normal compliance.

The tympanometric peak pressure point (TPPP) is the amount of pressure at which maximal compliance is reached. In other words, this value represents the pressure of the middle ear system. In a normal middle ear system, the TPPP is produced at ambient atmospheric pressure, usually around 0 daPa, but this can vary slightly between individuals. Negative pressure is often seen with eustachian tube dysfunction or retracted tympanic membranes. At times, a tympanogram may appear “flat” with no measurable TPPP. This can be a result of a tympanic membrane perforation, as sound is transmitted through the middle ear system across pressure changes, or middle ear effusion as fluid prevents the tympanic membrane from responding.

Ear canal volume is measured as the amount of air in front of the probe during tympanometry testing. In a normal ear, air space will begin at the end of the probe and stop at the tympanic membrane. If a tympanic membrane perforation is present, however, the volume will be calculated from the end of the probe tip through the middle ear cavity and a larger ear canal volume will be noted.

A type A tympanogram is usually indicative of normal middle ear function. While the two subtypes of a type A tympanogram, type As and type Ad, can be variants of normal, they may also indicate a middle ear abnormality. A type As tympanogram, one with a shallow peak, may indicate stiffening in the middle ear system, such as otosclerosis. A type Ad tympanogram, one with a larger peak, can indicate hypermobility which can occur with ossicular chain discontinuity or in the elderly population as skin, including the eardrum, losses elasticity.

A type B tympanogram, when the curve is completely flat and there is no peak, occurs with either a tympanic membrane perforation or with fluid in the ear as both pathologies result in no eardrum movement. With this curve type, the clinician will also take the ear canal volume into account as a larger ear canal volume may point to a perforation whilst a normal volume could indicate fluid in the ear.

A type C tympanogram shows negative pressure in the middle ear space. This occurs most often with eustachian tube dysfunction. When functioning properly, the eustachian tube equalizes pressure in the middle ear. With eustachian tube dysfunction, the air pressure is not equalized, and the eardrum becomes retracted, resulting in this curve type.