How do I test for room treatment ?

[twostone]

I was scanning thru the different post and seen a post about room acoustics. What I was wondering how do you measure the room acoustics I have free shareware for testing and what am I testing for or should I say what is the flat freqz. I'm testing for. I'll be using Audio test bench. I'll be testing a room 13.5X10.5 with 10' ceilings also has a 4X5 window in center of room any and all suggestions welcome, thanks.

 

[bubbagump]

Well, the most basic way is to use a measurement microphone. You can either use a Real Time Analyzer or record pink noise played into the room and then use your software to see where your peaks and valleys are. You usually want to place your measurement mic at the place you will be listening at as you will get different readings at different parts of the room. Of course you want to have a reading and treat for the place you will be listening.

 

[twostone]

I know about the test mic. I have a Behr. test mic but WTF am I measuring with a pink noise I don't understand the readings I have all peaks no valley WTF this mean I'm getting is their a reference chart for flat frqz. I'm confused.

 

[rayc]

Go to the RealTraps site & download their free graph & sound source - it works well. You'll need to borrow or buy a SPL meter - they're pretty cheap though.
You save the download to a cd. play the CD in the room with the SPL at ear height in the listening/mastering position & record the SPL on the accompanying graph. This'll show you where you have peaks & throughs in specific frequencies which you can then address with bass traps etc etc etc.

 

[twostone]

Thanks rayc you da man, I appreciate the web link, reaally helped me out.

 

[fraserhutch]

Go to the RealTraps site & download their free graph & sound source - it works well. You'll need to borrow or buy a SPL meter - they're pretty cheap though.
You save the download to a cd. play the CD in the room with the SPL at ear height in the listening/mastering position & record the SPL on the accompanying graph. This'll show you where you have peaks & throughs in specific frequencies which you can then address with bass traps etc etc etc.

Speaking of SPL meters, anyone got a good recommendation on an accurate one?

 

[c7sus]

Stand in the middle of your room and clap your hands.

Hear that quick echo???

It's called slap. You don't want that in your mics.

That's the most simple test of all.

Does your mix have LESS BASS on other systems??? Like your car, a stereo, etc.

That's the result of bass buildup.

the fix for that is treating the corners of your room with rigid fiberglass soundboard.

Every room has resonant frequencies. It's a physics thing. The idea is to minimize those resonant frequencies, knock them back into line with the rest of the spectrum.

Check out John Sayers' site and Ethan Winer for a couple different takes on how to address these issues.

 

[c7sus]

Speaking of SPL meters, anyone got a good recommendation on an accurate one?

Radio Shack supposedly markets a cheap SPL meter that works well.

 

[bubbagump]

Yeah, the Radio Shack SPL meter is as good as any.

 

[fraserhutch]

Hmmm, I've heard that the Radio Shck meter is wildly inaccurate in the higher frequencies.

I guess it wouldn't hurt to try it at the price.

 

[bubbagump]

For basic SPL of pink noise to calibrate against (or to use to measure the kids next door because you are a fuddy can want to call the cops ) , it is fine... Most computer based RTAs and measurement softwares want to calibrate the pink noise it puts out so it knows that X db out translates to 85db or whatever other value at the listening positon in the room. But no, you don't want to use it for really critical stuff that is high frequency heavy. And really, for room treatment purposes, we are much more concerned about the low end as the high end is controlled pretty easily.

 

[bennychico11]

like bubba said, I wouldn't use an SPL meter when concerned about treating the room....it really isn't going to show much. It will just tell you how loud the sound is coming out of your speakers at that position...it's not going to tell you where the problematic frequencies are unless you test each and every individual frequency. And even then, the mic isn't the greatest at all frequencies (I think I read it doesn't go beyong 8kHz?). Plus, the SPL meter only gives whole numbers.
Also, if you plan on analyzing your room using software and a test microphone...you need to keep in mind the effect the converters/preamps will have on the signal going into the computer. It can give you a unreliable reading, especially if using a typical sound blaster card. Take a look at this calculator to help with information on a typical rectangular room before doing a RTA test.
http://realtraps.com/modecalc.htm

 

[mjbath]

Can anyone put a link to a real time analyzer or software that will work on Windows 8? This thread isn't really clear on what needs to be done to analyze a rooms problem frequencies and the stuff on realtraps is still ambiguous in terms of where to get anything to test your room? It just says, "I've got a fever and the only cure is more bass traps". I looked at the SPLs available on Amazon (including the Radio Shack one) and I don't think that's what I need. I thought I would need something that generates sound at specific frequencies, records the output (for how it is reflected/amplified in the room) and then gives me the nice chart they show in their demos. The Audio Test Bench doesn't seem to work at all... is there any nice step by step guide to arrive at a result like they have in the realtraps or other videos so I can move things around and retest for comparison? If I had that I would be more willing to sink some money into treating my room if I knew what I was improving with any given additional treatment.

 

[JimmyS1969]

Here man. This is the most used program for testing room acoustics. Click on 'Here' for the link to REW. Yes you need to register for download, but it not a spam site.

 

[BroKen_H]

A lot of smart phones have free apps that do SPL and they're fairly accurate.

 

[Tom Hicks]

the guitar player in my brother's band recently built a control room and asked me to help him figure which resonant frequencies to tame. we used pink noise:

High Quality Pink Noise | wav mp3 Audio Files Download

a behringer ECM8000 measurement mic:

Behringer: MEASUREMENT CONDENSER MICROPHONE ECM8000

and voxengo span:

Real-time audio spectrum analyzer plugin (AU, VST, VST3) - Voxengo SPAN - Voxengo

i also gave him the REW software:

REW - Room EQ Wizard Room Acoustics Software

but he decided this other way was far simpler.

 

[bouldersoundguy]

Real time measurement isn't really up to sorting out room issues. You need something a bit more sophisticated. REW will do it. SMAART is probably the most popular professional software for this.

 

[smitco]

hey guys If im checking my room with a app and pink noise, how do I actually know what frequency needs to go up or down? which frequency in the chart is actually at the right level to begin with?
I cant seem to find that answer anywhere

 

[ecc83]

Err? SPL meters are "weighted".
That is they measure sound pressure levels according to a response curve that is relevant to the type of noise, the situation and some times the purpose of the test.
I would have THOUGHT a room response test should be done using a flat response microphone (don't stint here go B&K!) but then the software might specify a certain weighting?

To my way of thinking, the room's the room? You can bass trap it a bit but without major work you cannot change the basic response. FAR more important to my mind would be getting the monitors calibrated for a repeatable listening levels and for that any cheapo $20 meter will do, best if it has the "C" weighting.

But that is just an old valve jockey's view!


Dave.