Welch Allyn MicroTymp 3 portable tympanometric instrument - User Manual - Manual (Page 32)

32 Interpreting test results Welch Allyn MicroTymp3 portable tympanometric instrument
Gradient (width) measurements (226 Hz only)
When a tympanometric tracing is complete, the device measures the gradient or width of
the tympanogram. If the gradient is abnormal, an asterisk will appear on the LCD under
GR/A for the adult's ear (greater than 10 years of age), or GR/C for the child's ear (10 years
of age or younger). A sample of the Liquid Crystal Display appears below.
226-Hz mode
Normative values
The normative values presented in the table below are taken from a study by Margolis and
Heller (1987) and from the "Guidelines for Screening for Hearing Impairments and Middle
Ear Disorders" (1990).
-400 -200 0 200
2
0.5
0
1.0
1
GR
A
GR
C
PRESSURE - daPa
Ya - mmho
+200 Vea - cc
Normal static
admittance and
TPP (Adults) Normal static
admittance and
TPP (Children)
Admittance
axis
Pressure
axis
Gradient
(Width) Adult
Gradient
(Width) Child
Note For purposes of tympanometric norms, an adult is defined as a person 10 years of
age or older, and a child as under age 10.
Normative tympanometric values (226 Hz)
Tympanometric Measurement Child's Ear
(Under Age 10)
90% Range Adult's Ear
(Age 10 & Over)
90% Range
Peak Ya
(Positive Tail Compensation) 0.2 to 0.9 mmho 0.3 to 1.4 mmho
Gradient (GR)
(Tympanometric Width) 60 to 150 daPa 50 to 110 daPa
Tympanometric
Peak Pressure (TPP) -139 to +11 daPa -83 to 0 daPa
Equivalent Ear Canal
Volume (Vea) 0.4 to 1.0 cc 0.6 to 1.5 cc