Shadow 7D
Member
Manco your math sucks
you are thinkin 2+2
when this is a CURVE, 2*2+2*2 does not = 4*2
you are thinkin 2+2
when this is a CURVE, 2*2+2*2 does not = 4*2
Hearing Damage: .40 S&W vs .44 Special?
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It has been mentioned that the decibel scale is logrithmic (sp?), but I'm not sure everyone quite grasps exacty what that means. The scale isnt linear, meaning the relationship of 140 decibels to 150 decibels isnt the same as the relationship between $140 and $150. As I understand it from the examples I saw when trying to learn about it, a 150 decibel sound impulse is twice the sound intensity od a 140 decibel impulse. Like the Richter scale used for earthquakes, a magnitude 7 quake isnt twice as powerful as a 3.5, it's more like dozens of times more powerful. Each increment of the scale isnt a linear progression, it multiplies with each step. So yes, a "small" difference in noise level can make a difference in hearing damage. Another thing I read but do not entirely understand in it's techical form, but do understand in its practical form, is the decibel scale does not take into account the full aspect of a sounds scale, meaning it's only a partial implication of a sound. Sounds have depth or pitch differences (as in across a broadband scale)that the decibel scale doesnt account for. The decibel scale is more like a single dimensional image. Even tho we know there's more than one dimension to what it's trying to replicate or represent, the image doesnt capture the full dimension of it. This is what many are saying when they say a 357 magnum sounds much harsher than a large bore, even tho the decibel level may be similar.
And yes, I make my determinations on what guns I prefer to use partially based on the likelyhood of hearing damage. In my experience a 44 magnum with medium level loads is not nearly as painful or damaging as a full power 357 magnum.
I'd be happy for someone with a clearer way to describe the decibel scale to step forward and explain exactly how the levels relate to one another.
And yes, I make my determinations on what guns I prefer to use partially based on the likelyhood of hearing damage. In my experience a 44 magnum with medium level loads is not nearly as painful or damaging as a full power 357 magnum.
I'd be happy for someone with a clearer way to describe the decibel scale to step forward and explain exactly how the levels relate to one another.
Harley Quinn
Member
I really like Wiki...
http://en.wikipedia.org/wiki/Decibel
But you have to take the time to read or go find it and post the link for others
http://en.wikipedia.org/wiki/Decibel
But you have to take the time to read or go find it and post the link for others
I disagree. If there is something about sound attenuation that I don't understand and you do, then please enlighten us. But the math itself is exceedingly simple:
dB = 10log10(P1/P0)
P1/P0 = 10^(dB/10)
My point was that if hearing protection devices and NRR ratings worked in the manner that most people think that they do, then each device that has a 30 dB NRR, for example, would attenuate sound intensity by a factor of 10^(-30/10) = 1/1000. If two such devices were used, one layered on top of the other as in the case of muffs over plugs, then it would follow that each would contribute a factor of 1/1000, and (1/1000)*(1/1000) = 1/1000000. Plugging this back into the formula for dB, we get -60 dB, or in other words an attenuation of 60 dB. Mathematically it is equivalent to simply adding their NRRs together: 30+30 = 60. That's how the math actually works, contrary to other theories I've seen.
Then I explained why this is not the observed attenuation of wearing muffs over plugs (not even close!), and why you can't really combine the NRRs (which are not exactly what people think they are in the first place) of any practical devices together using simple math at all--it just doesn't make sense because of the physics involved (namely that the attenuation of the human body must also be taken into account, not just that of the devices).
What exactly are you talking about?
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In terms of power 150 dB is actually 10 times as intense as 140 dB. Mathematically, it works out this way: 10^((150-140)/10) = 10 (which is a ratio). Yes, I just subtracted one dB value from another. One of the main reasons that logarithms are used is simplified mathematics for those who understand them.
The probable reason you've read/heard that a 10 dB difference means 2 times the intensity is that this also takes into account both the typical signal response of the human ear and the typical perception of the auditory system in humans. These relationships are actually far more complex and vary by frequency for one thing, but sounding twice as loud at 10 times the actual intensity is a common and often useful rule of thumb. We just have to be careful to note which of these we're using.
Correct, and I touched on this briefly in a previous post in this thread.
Yes, different loads in different guns can sure sound different, and I believe that this difference can correlate with greater damage in some cases because the ear is more fragile at some frequencies (namely higher ones) than others.
The formulas I included in my last post and the examples I showed there and in this post pretty much cover it (given a sufficient background in math). A 10 dB difference (as in addition and subtraction) is equivalent to a ratio (as in multiplication and division) of 10 in the actual values being compared. This implies that a 20 dB difference is equivalent to a ratio of 100. In general, when you add dB values, you multiply the ratios; and when you multiply a dB value by a constant, you raise the actual ratio to the power of that constant.
I wouldn't rely on Wikipedia without first verifying that its information on a topic is correct, but in this case they're using the same formula that I learned in school and elsewhere.
Shadow 7D
Member
Ok, Manco
I take it back, your math is OK
what you are looking at is the Y axis of a curve,
but you have to translate that into Db, which is the X axis of a parabola, so, since you are talking orders of magnitude, that reduction, is VERY significant on the Y, but only represents a SMALL X axis movement.
Hence the talk of your standard parabola, or curve Y=X^2
I take it back, your math is OK
what you are looking at is the Y axis of a curve,
but you have to translate that into Db, which is the X axis of a parabola, so, since you are talking orders of magnitude, that reduction, is VERY significant on the Y, but only represents a SMALL X axis movement.
Hence the talk of your standard parabola, or curve Y=X^2
Shadow 7D
Member
Brickeye graph one
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