jaddie
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When is too loud?
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xnor
Headphoneus Supremus
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And it's definitely too late when you stop hearing the music.
RevMen
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Quote:
You're confusing the concepts of hearing threshold and hearing damage. When you say A-weighting is "correct" at 40 phons, what you mean is it's better suited for considering audibility at low levels. That doesn't make it "invalid" at higher levels.
A-weighting serves other purposes beyond assessing audibility. No weighting curve is "invalid" for any situation. There are better filters for certain jobs but they're all meaningful as long as you're consistent and you know what you're measuring. The only time it makes logical sense to compare A-weighted levels to C-weighted is when you're trying to get a feel for low frequency content.
A-weighting is used almost exclusively in the world of hearing conservation for determining hearing risk, because A-weighting is actually pretty compatible with the middle ear's transfer function. The middle ear is how airborne sound gets to your cochlea, which is what we need to consider most.
Using A-weighting to measure sound levels from any source, be it a machine or a PA, with the goal of limiting hearing loss is absolutely correct. Using C-weighting is not a good choice.
You're confusing the concepts of hearing threshold and hearing damage. When you say A-weighting is "correct" at 40 phons, what you mean is it's better suited for considering audibility at low levels. That doesn't make it "invalid" at higher levels.
A-weighting serves other purposes beyond assessing audibility. No weighting curve is "invalid" for any situation. There are better filters for certain jobs but they're all meaningful as long as you're consistent and you know what you're measuring. The only time it makes logical sense to compare A-weighted levels to C-weighted is when you're trying to get a feel for low frequency content.
A-weighting is used almost exclusively in the world of hearing conservation for determining hearing risk, because A-weighting is actually pretty compatible with the middle ear's transfer function. The middle ear is how airborne sound gets to your cochlea, which is what we need to consider most.
Using A-weighting to measure sound levels from any source, be it a machine or a PA, with the goal of limiting hearing loss is absolutely correct. Using C-weighting is not a good choice.
RevMen
New Head-Fier
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It turns out they're not too bad if what you're measuring doesn't have heavy low frequency and you're using the A filter (which probably all of them do). I saw a paper on this at a conference in February, I think they determined that they're accurate to within ~3 dBA. Definitely accurate enough to get a sense of whether your hearing is in danger.
It turns out they're not too bad if what you're measuring doesn't have heavy low frequency and you're using the A filter (which probably all of them do). I saw a paper on this at a conference in February, I think they determined that they're accurate to within ~3 dBA. Definitely accurate enough to get a sense of whether your hearing is in danger.
Greenleaf7
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Quote:
It's certainly pretty accurate when compared to a Radioshack SPL meter as seen here.
http://www.youtube.com/watch?v=6vQeT2QPo2c
It's certainly pretty accurate when compared to a Radioshack SPL meter as seen here.
http://www.youtube.com/watch?v=6vQeT2QPo2c
jaddie
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Agreed with all the above. However, if a real SPL measurement is required, A-weighting is not a good choice. It's also wrong if trying to use an RTA to judge mix spectral balance at concert SPL.
RevMen
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What is a "real SPL measurement?"
Why wouldn't you want to use an RTA to check spectral balance? What other options are there?
Why wouldn't you want to use an RTA to check spectral balance? What other options are there?
RonaldDumsfeld
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This article covers the topic pretty well. Including a useful n SPL to RL sounds table.
http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm
http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm
jaddie
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Quote:
The article quoted does a good job. Real meaning "actual" as opposed to Weighted.
Quote:
I said I don't use an RTA much to check spectral balance, and that I take exception to putting an A weighting curve head of an RTA used for checking spectral balance.
The concept is, watch an RTA and ideally you see something like an average flat response when its mixed for spectral balance. Sorry, that doesn't work, and anyone mixing music would know that already. An RTA shows constantly changing in response to input, so determining a long term average would take extended time integration (which impedes your ability to respond), or "visual averaging", prone to error. What's really needed is a 20 second time "window" that is constantly averaging the last 20 seconds, and some software can do that, but the resulting display is obviously quite slow. The real goal isn't a flat display anyway, it would be a spectrum that faithfully matches the original music. Now to all of that we add a weighting curve, which does not represent equal loudness at high SPL, further introducing error.
I don't use an RTA as a mixing aid because I mostly don't know what the spectrum should be, but I do know that a long term average of any music is never flat, even without an A weighting curve added. Every piece of music is different, but most music shows lower energy in LF and HF areas, so adjusting for a "flat" display would be artificially pushing up bass and treble, in very simple terms. And, where is that RTA getting its signal? A calibrated mic in the FOH mix position, or console out? Again, two very different samples.
So there's really limited value. I do appreciate being able to see a feedback ring, but hopefully those are mostly subtle and tuned out before a live performance, and frankly, by the time I look at the RTA to find it, I've pretty much already decided what frequency it is and started to take action. There's always someone crowding the stage monitor, though.
There is only one good option for judging spectral balance: your own hearing.
The article quoted does a good job. Real meaning "actual" as opposed to Weighted.
Quote:
I said I don't use an RTA much to check spectral balance, and that I take exception to putting an A weighting curve head of an RTA used for checking spectral balance.
The concept is, watch an RTA and ideally you see something like an average flat response when its mixed for spectral balance. Sorry, that doesn't work, and anyone mixing music would know that already. An RTA shows constantly changing in response to input, so determining a long term average would take extended time integration (which impedes your ability to respond), or "visual averaging", prone to error. What's really needed is a 20 second time "window" that is constantly averaging the last 20 seconds, and some software can do that, but the resulting display is obviously quite slow. The real goal isn't a flat display anyway, it would be a spectrum that faithfully matches the original music. Now to all of that we add a weighting curve, which does not represent equal loudness at high SPL, further introducing error.
I don't use an RTA as a mixing aid because I mostly don't know what the spectrum should be, but I do know that a long term average of any music is never flat, even without an A weighting curve added. Every piece of music is different, but most music shows lower energy in LF and HF areas, so adjusting for a "flat" display would be artificially pushing up bass and treble, in very simple terms. And, where is that RTA getting its signal? A calibrated mic in the FOH mix position, or console out? Again, two very different samples.
So there's really limited value. I do appreciate being able to see a feedback ring, but hopefully those are mostly subtle and tuned out before a live performance, and frankly, by the time I look at the RTA to find it, I've pretty much already decided what frequency it is and started to take action. There's always someone crowding the stage monitor, though.
There is only one good option for judging spectral balance: your own hearing.
RevMen
New Head-Fier
I still don't follow you. How does weighting make your measurement not "real?" What purpose would an unweighted measurement serve? I assume we're still talking about broadband, SLM type measurements, here. The only time I've ever encountered a use for an unweighted broadband measurement is for instantaneous peak pressures for things like gunshots, and I'd be surprised if you had that type of need for mixing live music.
RevMen
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It's confused. It can't decide if it's talking about RMS or peak (peak to peak? or just peak?). It can't decide if it's talking about broadband or 1-kHz. It feels like a translation issue.
It's confused. It can't decide if it's talking about RMS or peak (peak to peak? or just peak?). It can't decide if it's talking about broadband or 1-kHz. It feels like a translation issue.
jaddie
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Yes, the translation is a little ragged, but...
Quote from that site: "Sound pressure levels are measured without weighting filters" is fairly straight forward.
[size=medium]This next bit is rough," The values are averaged and can differ about ±10 dB", but I think what he's saying is watching a meter during music there can be readings that change as much as 10dB. By "averaged", I think he means the meter is changing and the operator visually averages the reading.[/size]
[size=medium]"With sound pressure is always meant the root mean square value (RMS) of the sound pressure, without extra announcement." Again, ragged translation, but if you just drop "without extra announcement", it's fine.[/size]
[size=medium]This one is confusing though, "The amplitude of the sound pressure means the peak value." Translated, hopefully more accurately, "The sound pressure measurement is the highest reading seen on the RMS-resonding SPL meter".[/size]
As to the validity of A-weighted concert level measurements, have a quick look at this, which explains it better than I've been doing:
http://en.wikipedia.org/wiki/A-weighting
Particularly note the statement, "the use of A-frequency-weighting is now mandated for all these measurements, although it is badly suited for these purposes, being only applicable to low levels so that it tends to devalue the effects of low frequency noise in particular."
And, the statement, "A-weighting is only really valid for relatively quiet sounds and for pure tones as it is based on the 40-phon Fletcher–Munson curves which represented an early determination of the equal-loudness contour for human hearing."
The paragraph that follows that last links the A-weighting problem with the development of ISO-226.
And this reference: http://home.mchsi.com/~dmaguire/dba-djm.pdf If you don't want to read the entire thing, go to section 6., the conclusion.
All I'm trying to say is, we MUST us the A-weighting curve only to correlate new measurements with old ones, or those taken by others using the A-weighting curve. Concert level measurements taken with an A-weighted meter do not reflect reality, either quantitatively or perceived. And judging spectral balance with an A-weighted RTA would be pretty misleading, for all the previously mentioned reasons. C-weighting, for quantitative SPL, would be closer to accurate. ISO-226 would be more appropriate for perceived SPL.
Quote from that site: "Sound pressure levels are measured without weighting filters" is fairly straight forward.
[size=medium]This next bit is rough," The values are averaged and can differ about ±10 dB", but I think what he's saying is watching a meter during music there can be readings that change as much as 10dB. By "averaged", I think he means the meter is changing and the operator visually averages the reading.[/size]
[size=medium]"With sound pressure is always meant the root mean square value (RMS) of the sound pressure, without extra announcement." Again, ragged translation, but if you just drop "without extra announcement", it's fine.[/size]
[size=medium]This one is confusing though, "The amplitude of the sound pressure means the peak value." Translated, hopefully more accurately, "The sound pressure measurement is the highest reading seen on the RMS-resonding SPL meter".[/size]
As to the validity of A-weighted concert level measurements, have a quick look at this, which explains it better than I've been doing:
http://en.wikipedia.org/wiki/A-weighting
Particularly note the statement, "the use of A-frequency-weighting is now mandated for all these measurements, although it is badly suited for these purposes, being only applicable to low levels so that it tends to devalue the effects of low frequency noise in particular."
And, the statement, "A-weighting is only really valid for relatively quiet sounds and for pure tones as it is based on the 40-phon Fletcher–Munson curves which represented an early determination of the equal-loudness contour for human hearing."
The paragraph that follows that last links the A-weighting problem with the development of ISO-226.
And this reference: http://home.mchsi.com/~dmaguire/dba-djm.pdf If you don't want to read the entire thing, go to section 6., the conclusion.
All I'm trying to say is, we MUST us the A-weighting curve only to correlate new measurements with old ones, or those taken by others using the A-weighting curve. Concert level measurements taken with an A-weighted meter do not reflect reality, either quantitatively or perceived. And judging spectral balance with an A-weighted RTA would be pretty misleading, for all the previously mentioned reasons. C-weighting, for quantitative SPL, would be closer to accurate. ISO-226 would be more appropriate for perceived SPL.
RevMen
New Head-Fier
Again, you're confusing audibility and perceived loudness with other reasons for measuring sound. Recall that phons are based on perceived loudness. A-weighting is an effort produce a single-number representation of sound that roughly corresponds to human perception in that area. C-weighting for higher (100?). Again, this is human perception.
The OSHA/NIOSH/every-other-organization-concerned-with-hearing-conservation measurements that started this conversation are not concerned with human perception of a sound, but with its ability to cause damage to hair cells. This is independent of and only somewhat related to human perception. It is a physical phenomenon, not psycho-acoustical. It just so happens that A-weighting also works pretty well for predicting damage to our hearing. It's a different application for the concept, apart from perception. Whether or not the C-weighting scheme works better for perception at higher levels is irrelevant.
There are a handful of papers showing that A-weighting isn't ideal for hearing conservation, including the one you linked to, and I am certainly in the camp that says reducing noise exposure to a single number gives an incomplete picture. But there are also multiple handfuls of papers showing that A-weighting works reasonably well as a predictor for hearing loss, as long as we choose the correct criterion and exchange rate.
The reason you "MUST" use A-weighting to measure levels that individuals in your venue are exposed to is the vast majority of literature and understanding in hearing conservation is based on A-weighted, broadband levels. For better or for worse. It is what we have, even if it's not ideal.
It's not possible to reject the use of A-weighting for this task because it leaves you with no point of reference. You can't just decide to use C-weighting or Z-weighting in place of A, because you can never compare measurements from different weighting schemes. If your criteria are based in dBA, you must measure dBA or your measurements are meaningless.
What does using C-weighting tell you about the sound you're measuring? It gives you a better understanding of the perceived loudness of the program material, sure, but what do you do with that information? Serious question.
The OSHA/NIOSH/every-other-organization-concerned-with-hearing-conservation measurements that started this conversation are not concerned with human perception of a sound, but with its ability to cause damage to hair cells. This is independent of and only somewhat related to human perception. It is a physical phenomenon, not psycho-acoustical. It just so happens that A-weighting also works pretty well for predicting damage to our hearing. It's a different application for the concept, apart from perception. Whether or not the C-weighting scheme works better for perception at higher levels is irrelevant.
There are a handful of papers showing that A-weighting isn't ideal for hearing conservation, including the one you linked to, and I am certainly in the camp that says reducing noise exposure to a single number gives an incomplete picture. But there are also multiple handfuls of papers showing that A-weighting works reasonably well as a predictor for hearing loss, as long as we choose the correct criterion and exchange rate.
The reason you "MUST" use A-weighting to measure levels that individuals in your venue are exposed to is the vast majority of literature and understanding in hearing conservation is based on A-weighted, broadband levels. For better or for worse. It is what we have, even if it's not ideal.
It's not possible to reject the use of A-weighting for this task because it leaves you with no point of reference. You can't just decide to use C-weighting or Z-weighting in place of A, because you can never compare measurements from different weighting schemes. If your criteria are based in dBA, you must measure dBA or your measurements are meaningless.
What does using C-weighting tell you about the sound you're measuring? It gives you a better understanding of the perceived loudness of the program material, sure, but what do you do with that information? Serious question.
deltawave
New Head-Fier
I ran a rehearsal for 2 bands tonight, 90-100 DBA the whole time, I'd have to say that if I were to run C weighted it would be a very inaccurate measurement for what I do every day.
Best of luck with your mixing/measuring, I'll be sticking with my Outline audio, Avid Venue, and SMAART rig for now
Where do y'all mix at?
Best of luck with your mixing/measuring, I'll be sticking with my Outline audio, Avid Venue, and SMAART rig for now
Where do y'all mix at?
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