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Sound exposure level (SEL) is a logarithmic measure of the sound exposure of a sound relative to a reference value. Sound exposure level, denoted L E and measured in dB , is defined by [ 1 ]
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Direct comparison with A-weighted sound pressure level, which is used for many other environmental sound measurements, is not possible because PNdB is a noisiness metric rather than a sound pressure metric. The term "cumulative" EPNdB is the combination of the noise margins from the three ratings.
Sites for launching large rockets are often equipped with a sound suppression system to absorb or deflect acoustic energy generated during a rocket launch. As engine exhaust gasses exceed the speed of sound, they collide with the ambient air and shockwaves are created, with noise levels approaching 200 db.
The Sound Reduction Index is expressed in decibels (dB). It is the weighted sound reduction index for a partition or single component only. This is a laboratory-only measurement, which uses knowledge of the relative sizes of the rooms in the test suite, and the reverberation time in the receiving room, and the known level of noise which can pass between the rooms in the suite by other routes ...
Traditional measures of suppressor noise reduction have focused on the change in the peak sound pressure level between suppressed and unsuppressed conditions. Because of the MIL-STD 1474D, the ability to reduce the suppressed level to below 140 dB peak sound pressure level (dB pSPL) was the goal for firearm suppressor manufacturers.
Combined with firearm sound suppressors, subsonic ammunition may significantly reduce sound levels compared to normal ammunition. [4] Specific reductions depend on the ammunition and suppressor. The peak sound pressure levels of a Remington 700 .223 caliber bolt-action rifle firing high-velocity (supersonic) ammunition using a GEMTECH G5-5.56 ...
[3] [10] Although specific regulations vary across the world, most workplace best practices consider 85 decibels (dB A-weighted) averaged over eight hours per day as the highest safe exposure level for a 40-year lifetime. Using an exchange rate, typically 3 dB, allowable listening time is halved as the sound level increases by the selected rate.