# OSHA's Noise Exposure Regulations **URL:** \ **Category:** Factual Questions\ **Created:** [November 18, 2012, 9:35pm UTC](https://boards.straightdope.com/t/oshas-noise-exposure-regulations/641442 "2012-11-18T21:35:21Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![Pitchmeister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pitchmeister/32/3459_2.png) [@Pitchmeister](https://boards.straightdope.com/u/Pitchmeister)\ **Post date:** [November 20, 2012, 10:53pm UTC](https://boards.straightdope.com/t/oshas-noise-exposure-regulations/641442/21 "2012-11-20T22:53:36Z")
> [@Surreal](#): > > 10 log(P2/P1) = 10 log(2) = 3 dB > > An increase of 10 dB is equivalent to a increase in the sound pressure level by a factor of 10. Nope. Your formula is correct for sound energy. For sound pressure, you need to square the two pressure terms you’re comparing, so you end up with 20 log(2), which equals 6 dB. An increase of 20 dB represents a tenfold increase in sound pressure. As for the OP, I would seriously question the accuracy of your measuring equipment - as you rightly noted, a maxed out audio system does not produce levels of 85 dB. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [November 21, 2012, 12:08am UTC](https://boards.straightdope.com/t/oshas-noise-exposure-regulations/641442/22 "2012-11-21T00:08:47Z")
> [@Anonymous User](#): > > I was wondering if maybe I could get a “pink noise” app on my phone, and then plug that in to my car audio system. That would be good for performance purposes. sure, there are any number of tone generator apps for Android that’ll put out pink noise. > [@](#): > > It’s a little hard to explain, but like I said above, I’m also trying to reference my dad’s car audio system to OSHA’s standards and “how loud” the music is. Like if you went to a night club to measure this (you probably wouldn’t), and you wanted to see how loud you could listen to music “that loud” for, then I would assume that you would set it to “A”. No. A-weighting was originally intended for characterizing _background_ noise levels. It doesn’t really apply to really loud sounds since human hearing is not linear with volume (see Fletcher-Munson curves.) For something at loud SPLs like a cranked-up car system or concert, no weighting should be used. see, the thing about A-weighting is it is supposed to be used at low to moderate SPL levels (up to about 85-90 dB) to try to characterize the specific frequency ranges that people can be exposed to which can cause the most apparent hearing damage. OSHA applies to job environments like factories or airport workers because they tend to be exposed to noisy shit for 6-10 hours a day, and can’t necessarily leave if they feel like it. OSHA standards do not apply to people going to a concert or cranking up their car stereo because those are not **occupations.** If the concert is too loud, you can leave. if your car stereo is too loud, turn the damn thing down. > [@](#): > > That’s the kind of thing I’m implying with my car audio system if that helps explain it better. Now, I have a feeling that for this kind of application, it would be better to actually play music because that’s what you actually listen to, and if I’m trying to compare the “A” reading to the OSHA regulations to see how long I can listen to it, then wouldn’t you want to play actual music? (That part is a little hard to explain) I get what you’re trying to say, but the problem is that music is a random, non-steady-state signal. To get any useful SPL measurements while playing music, you need a looooooooonnnnng averaging time, and I don’t think many low-cost SPL meters have that kind of averaging window. You could use one of the PC-based real-time-analyzers like TrueRTA, a decent microphone, and a calibrator. Then you could specify a large number of averages to get the avg SPL, and use peak hold to see the peaks. > [@](#): > > As far as, angling my meter right, how should I do it? Should I stick it up to the ceiling, or should I point it towards one of the speakers or place it in the shape of my ears (this is for when I’m measuring for health and safety concerns, or “A” frequency weighting). > > And how should I angle it when I’m in “C”? well, I’ve never looked into whether SPL meters use free-field or pressure microphones (I assume the latter) but it’s not about the direction it’s pointed, and the weighting is irrelevant. It’s about getting a spatial average of the SPL in a particular area. If I have to take a measurement in a car and I’m stuck with a single microphone, I’ll generally point it upward and move it in a horizontal circle about 10" diameter at the approximate position of the driver’s head for a reasonable number of averages. ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [November 21, 2012, 12:21am UTC](https://boards.straightdope.com/t/oshas-noise-exposure-regulations/641442/23 "2012-11-21T00:21:22Z")
> [@Pitchmeister](#): > > Nope. Your formula is correct for sound energy. For sound pressure, you need to square the two pressure terms you’re comparing, so you end up with 20 log(2), which equals 6 dB. An increase of 20 dB represents a tenfold increase in sound pressure. I stand corrected. Thanks. ---
**Author:** ![R3d\_Anonymous](https://avatars.discourse-cdn.com/v4/letter/r/aeb1de/32.png) [@R3d\_Anonymous](https://boards.straightdope.com/u/R3d_Anonymous)\ **Post date:** [November 21, 2012, 12:57am UTC](https://boards.straightdope.com/t/oshas-noise-exposure-regulations/641442/24 "2012-11-21T00:57:36Z")
> [@jz78817](#): > > sure, there are any number of tone generator apps for Android that’ll put out pink noise. > > No. A-weighting was originally intended for characterizing _background_ noise levels. It doesn’t really apply to really loud sounds since human hearing is not linear with volume (see Fletcher-Munson curves.) For something at loud SPLs like a cranked-up car system or concert, no weighting should be used. > > see, the thing about A-weighting is it is supposed to be used at low to moderate SPL levels (up to about 85-90 dB) to try to characterize the specific frequency ranges that people can be exposed to which can cause the most apparent hearing damage. OSHA applies to job environments like factories or airport workers because they tend to be exposed to noisy shit for 6-10 hours a day, and can’t necessarily leave if they feel like it. OSHA standards do not apply to people going to a concert or cranking up their car stereo because those are not **occupations.** If the concert is too loud, you can leave. if your car stereo is too loud, turn the damn thing down. > > I get what you’re trying to say, but the problem is that music is a random, non-steady-state signal. To get any useful SPL measurements while playing music, you need a looooooooonnnnng averaging time, and I don’t think many low-cost SPL meters have that kind of averaging window. You could use one of the PC-based real-time-analyzers like TrueRTA, a decent microphone, and a calibrator. Then you could specify a large number of averages to get the avg SPL, and use peak hold to see the peaks. > > well, I’ve never looked into whether SPL meters use free-field or pressure microphones (I assume the latter) but it’s not about the direction it’s pointed, and the weighting is irrelevant. It’s about getting a spatial average of the SPL in a particular area. If I have to take a measurement in a car and I’m stuck with a single microphone, I’ll generally point it upward and move it in a horizontal circle about 10" diameter at the approximate position of the driver’s head for a reasonable number of averages. I’m sorry, but I’m forced to use “C” weighting. Sound level meters usually only offer A/C weighting button. So, the closest I can get to no weighting is “C”, because that is flat for most of the time. Yes, but how can I actually determine how loud I can listen to music that loud for. That’s the question here. Should I take the “unweighted” (it really WON’T be unweighted, but close) sound level and compare it to the OSHA regulations, the NIOSH regulations? How can I actually know, how long I am aloud to be exposed to music that loud. And, mine averages the sound level over 1 second, so that’s pretty short… So are you trying to tell me: use “A” weighting for background/environmental noise measurements or for machines (with the intention to refer to OSHA) and use “C” weighting for music, and loud SPL’s above 85 dBA, or when measuring performance of things in order to get a fair, mostly unweighted value? (Sorry if I’m frustrating you; I’m just trying to understand how to use my sound level meter effectively). ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [November 21, 2012, 1:13am UTC](https://boards.straightdope.com/t/oshas-noise-exposure-regulations/641442/25 "2012-11-21T01:13:48Z")
you’re trying to do some things which your sound level meter wasn’t designed to do. ---
**Author:** ![R3d\_Anonymous](https://avatars.discourse-cdn.com/v4/letter/r/aeb1de/32.png) [@R3d\_Anonymous](https://boards.straightdope.com/u/R3d_Anonymous)\ **Post date:** [November 21, 2012, 1:14am UTC](https://boards.straightdope.com/t/oshas-noise-exposure-regulations/641442/26 "2012-11-21T01:14:39Z")
> [@jz78817](#): > > you’re trying to do some things which your sound level meter wasn’t designed to do. What things? And how is it not designed to do those things? [Previous page](https://boards.straightdope.com/t/oshas-noise-exposure-regulations/641442.md?page=1)