If the decibel scale is logarithmic, isn’t 33dB between 100 and 133 a much different amount in reality than 33dB is between 30dB & 63dB? So how can NRR 33 ear plugs reduce 60dB down to 30 while also reducing 140dB down to 110? Wouldn’t it only, say, reduce a 60dB noise by 33dB, but reduce a 140dB noise by a lesser amount? Does the ear plugs’ ability to reduce the sound increase with the volume?
If they really do subtract 33dB across the spectrum of dB ranges, then why are sub-33dB sounds still audible? Shouldn’t sounds around that range be effectively 0dB and inaudible?
If 60dB sounds are, say, 45dB with NRR33 earplugs, then are 100dB sounds actually 85 instead of 67? Or is there some mechanism enabling sounds that should be lowered to sub-40dB to be above 40, while also lowering 130dB to 100?
In: Physics
The ear plugs absorb ~99.97% of the sound and let 0.03% or 1/3000 through. If you have a louder sound they absorb more energy, but the fraction stays the same (approximately).
On a logarithmic scale, multiplying the power by a constant is converted to a constant difference in dB.
> then why are sub-33dB sounds still audible?
The fraction of the sound they absorb depends on the frequency. It’s technically 33 dB at some specific frequency and likely less elsewhere.
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