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•
Type B is a flat tympanogram with no discernible peak.
•
Type C is a tympanogram with the SA peak appearing to the left of the rectangle, thus showing a negative TPP (more
negative than -100 daPa).
•
In addition, Type D may be used to indicate a multiple peaked tympanogram.
Adult 226 Hz tymp classification system
MADSEN Zodiac uses the Adult 226 Hz norm originating partly from Jerger. The
determination of types A, Ad, As, B, and C is based on the location (pressure and
static admittance) of the peak of the tympanogram as shown:
•
B is used instead of As for curves with no significant peak.
•
Pressure limits: -100 to +50 daPa.
•
Static admittance limits: 0.3 to 1.7 mmho.
App. 1.2.3
ETF-I (Eustachian Tube Function - Intact)
ETF-I is done to examine how well the middle ear is ventilated through the Eustachian tube. Air must be able to pass
through the Eustachian tube in order to equalize the middle ear pressure.
For testing the tube function in ears with intact eardrums (ETF-I), multiple tympanograms are recorded with different
middle ear pressure equalization maneuvers done between the measurements. The tympanogram tympanometric peak
pressures are compared to evaluate whether pressure equalization is successful.
In general, people have a slight negative middle ear pressure (quite normal even with a fully functioning Eustachian tube).
A successful equalization of negative pressure will displace the tympanometric peak in a positive direction in the tym-
panogram. It is less common with standing positive pressure in the middle ear, due to the anatomical properties of the Eus-
tachian tube. The tube is likely to be forced open by the pressurized air itself. Equalization of positive pressure will
displace the tympanometric peak in a negative direction in the tympanogram.
Typical special equalization techniques used are the Valsalva and Toynbee maneuvers.
App. 1.2.4
Valsalva's Maneuver
This maneuver equalizes the pressure (or induces positive pressure) in the middle ear by forcing air through the tuba into
the middle ear cavity. This is a common procedure used for pressure equalization when diving or flying. In some ears, this
maneuver can also induce a standing positive pressure. However, as mentioned above, this is usually difficult to maintain
without the air spontaneously leaking out back through the tuba. The resulting tymp peak after this maneuver will often
appear around 0 daPa, ± approx. 15 daPa.
How to perform the maneuver
1. Instruct the patient to block the nostrils by pinching the nose using the thumb and index finger.
2. Instruct the patient to carefully blow some air out of the mouth but with the lips tightly sealed.
App. 1.2.5
Toynbee's Maneuver
This maneuver primarily creates a negative middle ear pressure since air will be evacuated from the middle ear through a
functioning tuba.
Otometrics - MADSEN Zodiac
App. 1 MADSEN Zodiac immittance methodology and features
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