Test Data   

Real-ear attenuation characteristics of the communications earplug per ANSI S3.19-1974 using standard and slim size eartips.  Test were conducted by Aearo Company's E·A·RCALSM Acoustical Laboratory, May 2000.  NRR per EPA-1979 is 29.5

Test Frequency (Hz)
Mean Attenuation (dB)
Standard Deviation (dB)
125
29.7
5.3
250
34.2
5.9
500
39.7
4.7
1000
42.1
5.1
2000
38.0
3.2
3150
43.2
3.2
4000
43.5
3.5
6300
47.5
4.5
8000
46.1
4.4

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Mean speech intelligibility in percent for HGU-56/P with CEP and HGU-56/P.  
Speech material was presented at constant speech levels for both devices.  

Device
Alone
Spectacles
CB Mask
HGU-56/P with CEP
92.0
92.2
90.1
HGU-56/P
71.1
55.8
53.6