Hearing protection information
The protective effect of hearing protection products is given in dB (decibels).
The SNR (Single Number Rating) indicates an insulation value averaged over the relevant frequencies. An SNR value of 35dB, for example, absorbs 100 dB and reduces it to 65 dB.
The HML values indicate how high sound reduction in three frequency ranges, H (high), M (middle) and N (low) is. These frequencies are:
H (High): between 2000 and 8000 Hz
M (Middle): between 1000 and 2000 Hz
L (Low): between 63 Hz und1000
The decibel scale is logarithmic. Noise exposure of 95 dB is perceived as twice as loud as 85 dB. Measured physically, this difference actually shows a tenfold increase of sound pressure.
Long-term, daily exposure to 85 dB is generally considered to result in hearing loss. Daily exposure of 8 hours at 85 dB is just as dangerous as 88 dB for 4 hours.