Average SPL

dwillis60

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This seems pretty basic but I can't seem to find the answer. I'm looking for a way to determine the average SPL (Average Db) for a typical SPL frequency run. The All SPL tab allows me to generate averages for several runs and perform other arithmetic calculations on runs A, B, etc.. I also came across the Db range under Tools>Info. I can also export all the data and import that into some kind of spread sheet application, but that seems really tedious if REW can calculate it's own averages.

I should also note that some type of average will occasionally pop up in the check off box at the bottom of the screen under the All SPL tab. But this is very inconsistent. Sometimes it appears and sometimes it does not. Moreover, it changes as soon as I move the cross hairs to another location.

I've searched the help menu but it leads me to the All SPL tab and averages for multiple runs. I've also searched this forum and Google--all with no luck.

Thanks for your help
 

Wayne A. Pflughaupt

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I'm looking for a way to determine the average SPL (Average Db) for a typical SPL frequency run.
Are you talking about averaging a single measurement sweep, or something else?

Regards,
Wayne
 

John Mulcahy

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REW doesn't make any calculation of the average SPL of a frequency response, though if you smooth it heavily you'll get a pretty good idea.
 

dwillis60

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Thanks for the information. A basic average for a single SPL sweep would be handy for any future versions. It would also be great to include a line indicating a +/- db range around that average, based on broadcast standards or perhaps another baseline.

Most of us home recording types are looking for a quick way of telling how flat our mixing rooms are. Nobody expects perfect flatness, but as we add room treatments it would be great to get the results to fall within a specified range around the average.

Thanks again for your information and for providing REW. It's been a great learning experience. Now I just have to get back to recording and songwriting. This audio measurement stuff is addictive!
 

Matthew J Poes

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Thanks for the information. A basic average for a single SPL sweep would be handy for any future versions. It would also be great to include a line indicating a +/- db range around that average, based on broadcast standards or perhaps another baseline.

Most of us home recording types are looking for a quick way of telling how flat our mixing rooms are. Nobody expects perfect flatness, but as we add room treatments it would be great to get the results to fall within a specified range around the average.

Thanks again for your information and for providing REW. It's been a great learning experience. Now I just have to get back to recording and songwriting. This audio measurement stuff is addictive!
What your trying to do isn’t really the right way to go about assessing the mix in room. The measurements are capturing a lot of information you don’t hear as it shows up in those graphs. As reflections are reduced you don’t necessarily see an increase in the smoothness. That would mostly happen at LF’s and it would take a lot of bass traps to see a substantial difference.

If you want to see the impact of absorption I think you are better off using something other than the steadystate. It’s good to look at but a better approach is to in the time domain. For anything under about 500hz I suggest using filtered impulse response at key frequencyies which match modes and boundary interference.

Wavelets found under the spectrogram is also good. I like those for a lot of reason. At LF’s it’s a good way to visualize the effect of reducing modal ringing. The steadystate shows this too but it’s still helpful to look at the time domain. It can show overall increase in LF decay. It can show groupdelay. And at HF’s it can better show reflections and diffraction interference effects and help depict how treatments are fixing things.

Finally, at HF’s, simply looking at the impulse can help identify reflections that you may be targeting. Myself, I don’t really think these are a problem. I’ve read the NRC research and IM convinced it’s right. Still, I know not everyone agrees.

@DanDan has been hanging around here and may have more insight.
 

dwillis60

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Thanks for the insight. My focus on the frequency response data is only part of my overall effort, and this thread was really just an attempt to clarify whether REW calculated an average for a single SPL run. So I'm not giving a lot of weight to the idea of a flat frequency response. It's one measure among many.

I also started diving into Waterfalls, Spectrograms, Impulse, RT60, etc. and I'm learning as I go along. Unfortunately, the learning curve is steep and I'm encountering stumbling blocks at every turn. It's fun and a good learning experience, but I wonder how long I can last.

I have quite a bit of treatment in my room, including bass traps and broadband absorption. Most of these panels are OC 703 placed at the standard positions, including ceiling-to-floor bass traps at the corners, broadband traps at the reflection zone, ceiling coverage at the mix position, and broadband absorbers on various walls. I'm also in the process of installing additional bass traps at the ceiling-wall position(s) and experimenting with desk/speaker placement.

Along the way, I'm using REW to help me judge how I'm doing and, perhaps, when to stop. It's partially a learning experience and an intellectual exercise. Ultimately, I may come to the sad realization that my room is my room, and that all the measurements in the world and all the acoustic treatment won't change that fact. Or, more likely, that any change will be marginal and diminishing--especially given the amount of treatment that has already been installed. Of course, it's better than watching the news or following the stock market!

Thanks again for your thoughtful input.
 

Matthew J Poes

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Thanks for the insight. My focus on the frequency response data is only part of my overall effort, and this thread was really just an attempt to clarify whether REW calculated an average for a single SPL run. So I'm not giving a lot of weight to the idea of a flat frequency response. It's one measure among many.

I also started diving into Waterfalls, Spectrograms, Impulse, RT60, etc. and I'm learning as I go along. Unfortunately, the learning curve is steep and I'm encountering stumbling blocks at every turn. It's fun and a good learning experience, but I wonder how long I can last.

I have quite a bit of treatment in my room, including bass traps and broadband absorption. Most of these panels are OC 703 placed at the standard positions, including ceiling-to-floor bass traps at the corners, broadband traps at the reflection zone, ceiling coverage at the mix position, and broadband absorbers on various walls. I'm also in the process of installing additional bass traps at the ceiling-wall position(s) and experimenting with desk/speaker placement.

Along the way, I'm using REW to help me judge how I'm doing and, perhaps, when to stop. It's partially a learning experience and an intellectual exercise. Ultimately, I may come to the sad realization that my room is my room, and that all the measurements in the world and all the acoustic treatment won't change that fact. Or, more likely, that any change will be marginal and diminishing--especially given the amount of treatment that has already been installed. Of course, it's better than watching the news or following the stock market!

Thanks again for your thoughtful input.
You are always welcome to share mdat files for specific feedback. It often allows us to dig in ourselves to see if we can find those elusive improvements.

I think the best way to do what you are trying to do may be through the EQ panel. You can fit a target curve and run it through the middle of your response curve. You can adjust the curve until it looks like a smooth line through your curve and you can assess the variance from there. You can even generate eq with various smoothness factors to see how much it needs to change to get to that target +\- level. I just wouldn’t put too much stock in that from a sound standpoint. It’s easy to make a response flat in room, but that doesn’t necessarily correlate with good sound.

When it comes to bass traps, you may find that at some point you can’t possibly get enough LF damping and you now have too much HF damping. In those cases you have to move to more efficient means of LF absorption.
 

dwillis60

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Did you try the eq idea?
No, not yet. I'm gradually making my way in that direction but I'm still playing with some of the other REW functions. Like I said above, the learning curve is fairly steep.

I glanced at the EQ tab but it's somewhat intimidating. I'm also not sure what my target curve would look like and how it would serve as a framework for comparison. I've read a little about the B&K curve and noticed a few folks suggesting that as a good solution for comparing room curves in a control room/home project studio setting. I even went so far as downloading raw B&K data thinking that I might somehow input that, perhaps using the EQ function. But that's as far as I went. Like I said, the EQ section is a little hard to figure out--at least for a beginner.
 

kapooranuj

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Ill post a tutorial when I get a chance on how to do what I’m saying.
Hey Matthew
Love your videos and the knowledge that you share. I have learnt a lot from you. Just started with REW.
For now, any chance of the tutorial you spoke of? If done already, then could you pls link me up.
 
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