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• For noise environments dominated by frequencies below 500 Hz, the C-weighted
environmental noise level should be used. Although hearing protectors can be
recommended for protection against the harmful effects of impulsive noise, the noise
reduction ratings (NRR) are based on the attenuation of continuous noise and may not be
an accurate indicator of the protection attainable against impulsive noise such as gunfire.
Attenuation Data
The Noise Reduction Rating (NRR) was obtained with the device powered Off. The NRR may
overestimate the hearing protection provided during typical use due to variation in fit, fitting
skill and motivation of the user. 3M recommends reducing the NRR by 50% or in accordance
with applicable regulations. Improper fit or inconsistent use of this device will reduce its
effectiveness in attenuating noise. Consult the fitting instructions illustrated in this instruction
manual for proper fit.
Example:
1. The environmental noise level as measured at the ear is 92 dB(A).
2. The NRR is 23 decibels (dB).
3. The level of noise entering the ear is approximately equal to 69 dB(A).
Note: 3M recommends fit testing of hearing protectors.
LABORATORY ATTENUATION
3M
UltraFit
Communication Eartips
TM
TM
Test frequencies (Hz) 125 250 500 1000 2000 3150 4000 6300
Mean attenuation (dB)
Standard deviation (dB)
3M
PELTOR
CCC-GRM-25 Communication Eartips
TM
TM
Test frequencies (Hz) 125 250 500 1000 2000 3150 4000 6300
Mean attenuation (dB)
Standard deviation (dB)
3M
Skull Screws
TM
TM
Test frequencies (Hz)
Mean attenuation (dB)
Standard deviation (dB)
36.2
33.7
5.1
5.2
34.5
30.6
4.2
3.9
Communication Eartips (not included)
125
250
36.3
35.7
39.8
5.3
5.5
34.7
32.0
34.5
5.5
3.9
3.4
36.3
35.2
35.5
4.1
3.0
3.5
500
1000
2000
3150
41.4
40.4
43.0
5.5
4.2
3.4
3
8000
37.4
35.6
38.0
5.3
6.5
4.4
8000
38.6
37.6
44.6
3.3
3.8
3.6
4000
6300
8000
41.9
48.2
46.0
4.6
3.5
4.6
ANSI S3.19-1974
CSA
NRR
CLASS
37.5
23
AL
5.4
ANSI S3.19-1974
CSA
NRR
CLASS
45.7
27
AL
4.3
ANSI S3.19-1974
CSA
NRR
CLASS
30
AL
4.2
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