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App. 1 MADSEN Zodiac immittance methodology and features
ured at 200 daPa (approximates the isolated ear canal component). In accordance with this, static admittance is often
referred to as the "peak to tail difference".
The SA is shown only when the baseline compensation is enabled, i.e. when the admittance is shown relative to the
baseline admittance.
When a 226 Hz tympanogram is shown in volume units, the term Static Compliance, SC, is used instead of SA.
Note
Static Admittance, SA, is the same as the ANSI S3.39-1987 peak compensated static acoustic admittance,
•
Peak Ytm.
Tympanometric Width, TW
Tympanometric Width, TW, provides a measure of the
sharpness, or steepness, of the tympanogram. TW is the
curve width at half the height of the curve (SA/2). TW is
measured in daPa in accordance with the illustration.
Y
. Admittance
X
. Pressure
Equivalent Ear Canal Volume, ECV
Equivalent Ear Canal Volume, ECV, is measured as the com-
pliance at +200 daPa ear canal pressure. Accordingly, the
ECV is only shown when a 226 Hz probe tone is used.
When using a higher frequency probe tone, the
Baseline Volume
Tympanometry type, "Type"
Tympanometry type, "Type", is a classification method of the shape of the 226 Hz tympanogram. This is the modified Jer-
ger classification system.
The classification is carried out in relation to a normative range shown as a rectangle in the tympanometry graph.
Note
This classification system does not take the tympanometric width or gradient into account.
•
•
Type A is a normal tympanogram with a single SA peak within the rectangle.
•
Type Ad is a high admittance tympanogram reaching above the rectangle.
•
Type As is a low admittance tympanogram with the peak below the rectangle.
142
EBV
,
, is shown instead of ECV.
Tympanometric Width
Fig. 1
Fig. 2
Measurement-plane tympanogram
Baseline compensation: OFF
Equivalent
SA+ECV = Total Admittance
A.
Otometrics - MADSEN Zodiac
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