For audiometric testing outside of noise attenuating test rooms, Natus recommends using earphones which feature passive
noise reduction. For the applicable earphone models, the attenuation is specified in the following table.
Sound attenuation values for earphones
Frequency
Attenuation
(Hz)
TDH39 with
MX41/AR cushion
(dB)
EAR 3A
(dB)
HDA300
(dB)
63
-
-
12.5
125
3
33
12.5
160
4
34
-
200
5
35
-
250
5
36
12.7
315
5
37
-
400
6
37
-
500
7
38
9.4
630
9
37
-
750
-
-
-
800
11
37
-
1000
15
37
12.8
1250
18
35
-
1500
-
-
-
1600
21
34
-
2000
26
33
15.1
2500
28
35
-
3000
-
-
-
3150
31
37
-
4000
32
40
28.8
5000
29
41
-
6000
-
-
-
6300
26
42
-
8000
24
43
26.2
Data obtained from manufacturer’s data sheet.
26
Aurical Aud
17 Technical specifications
