Frequency (Hz)	125	250	500	1000	2000	3150	4000	6300	8000	NRR
Mean Attenuation (dB)	32.5	34.7	31.4	33.0	33.4	39.4	37.6	37.2	37.0	26
Standard Deviation (dB)	4.3	4.0	3.2	2.5	2.6	4.3	4.0	4.7	3.7

Independently tested to ANSI S3.19-1974

 Low Frequencies

The ZEM reduces sounds in the low frequencies (125Hz to 500 Hz) better than most hearing protection products. These low frequency noises are the ones that mask speech communication.

Mid-Range

The flat attenuation characteristics in the speech range between 500 Hz and 2000 Hz is what distinguishes the ZEM. Because sound is reduced evenly, there is no distortion. The result is very high speech intelligibility.

High Frequencies

Attenuation increases appreciably above 2000 Hz, the most damaging frequencies to the human ear.