Thread: Ear Protection
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Old 12-12-2013, 02:29 PM
TWerner TWerner is offline
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Join Date: Jan 2012
Location: NC
Posts: 217
Default Re: Ear Protection

Originally Posted by beyondbetrayal View Post
also.. Not trying to argue with you here.. but the decibel scale is logarithmic , or exponential.
so 15 db at the top end is not the same as 15db at the bottom end.. your whisper at 30 is not half as loud as talking at 60

That's not argumentative, but I am very aware of the physics. For anyone who isn't, this may help:

10Log(P2/P1)=db - - - 10Log2=3.01 or about 3db.

so when pressure 2 (P2) is twice pressure 1 (P1), you call it a 3db increase. This doesn't mean 6db sounds twice as loud as 3db, just mean the energy is twice as high.

That's the easy part. The hard part is that our hearing isn't linear or logarithmic. Perceived acoustics are not well correlated with SPL/db. We use Sones to describe loudness or volume at 1000 hz, and at that frequency, people generally describe about a 10db increase as sounding "twice as loud". Pretty cool since it's actually >8 times the energy.

But, while you may hear a 10db decrease as a reduction of 50% at 1000 hz, it doesn't mean you'll hear a 10db decrease as a halving of volume at 100hz or 3000hz. That's why a 10db "flat" frequency reduction in ear plugs won't just half the volume. 90db at 3000hz will "sound" louder to us than 90db at 100hz. So a bass drum may not "sound" as loud as a guitar at the same spl, but it's still the same energy level. 90db at 1000hz sounds about the same volume as 100db at 100hz to us, despite the 100db being 8x the energy. You also may require more than 10db increase even at 1000hz to perceive a doubling of volume at higher db levels. Tricky stuff.

As BeyondBetrayal noted, drums have short peak levels, but I'd say they are still quite dangerous over time. Even the custom earplugs are cheap compared to losing your hearing.

Here's a good read that is low on physics :)
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