Service Manual
AT235
V
6.2 Reference values for stimulus calibration
Freq.
Reference Equivalent Threshold Sound Level
(RETSPL)
[dB re. 20 µPa]
Variation of Ipsi
stimulus levels
for different
volumes of the
ear canal
Relative to the
calibration
performed on an
IEC 126 coupler
[dB]
Sound
attenuation
values for
TDH39/DD45
earphones using
MX41/AR or
PN51 cushion
[dB]
ISO
3
89
-1
(Int
er
ac
ous
tic
s
St
an
dar
d)
ISO
3
89
-2
(Int
er
ac
ous
tic
s
St
an
dar
d)
Int
er
ac
ous
tic
s
St
an
dar
d
Int
er
ac
ous
tic
s
St
an
dar
d
Int
er
ac
ous
tic
s
St
an
dar
d
ISO
3
89
-4
(IS
O
87
98)
0.5 ml
1 ml
[Hz]
TDH39
EARtone
3A / IP30
DD65 v2 DD45 Probe NB
Stimulus
Correction
Values
R
ET
SPL
125
45
26
30,5
47.5 41
4
3
250
25.5
14
17
27
24.5 4
5
500
11.5
5.5
8
13
9.5
4
9.7
5.3 7
1000 7
0
4,5
6
6.5
6
9.7
5.3 15
1500 6.5
2
2,5
8
5
6
21 (1600 Hz)
2000 9
3
2,5
8
12
6
11.7
3.9 26
3000 10
3.5
2
8
11
6
-0.8
-0.5 31 (3150 Hz)
4000 9.5
5.5
9,5
9
3.5
5
-1.6
-0.8 32
6000 15.5
2
21
20.5 3
5
26 (6300 Hz)
8000 13
0
21
12
-5
5
24
WB
-8
-5
-8
-8
-5
7.5
3.2
LP
-6
-7
-6
-6
-7
8.0
3.6
HP
-10
-8
-10
-10 -8
3.9
1.4
*All figures in bold are Interacoustics Standard values.
