"Noising" a room?

s3 · Post by s3 » Tue Aug 19, 2003 6:45 pm

Ok, I have an SPL meter, I have a test tone cd, where can I read about what to do next?

Cheers,
S3

PS-the "Cheers" salutation was not stolen from John. It was however, stolen from a friend of mine after he moved to the other side of the country where I never get to see him anymore. Everytime he emailed me I thought, "what a great way to sign off". If you don't know why I added this, go to the "Studios Under Construction" category.

Ethan Winer · Post by **Ethan Winer** » Wed Aug 20, 2003 5:22 am

S,

> where can I read about what to do next? <

See the thread "Frequency Profile" elsewhere in this forum. It explains the pros and cons of pink noise and test tones in detail.

For an overall description of using pink noise to measure a room see that sidebar in my Acoustics FAQ, 10th in the list on my Articles page:

www.ethanwiner.com/articles.html

--Ethan

s3 · Post by s3 » Tue Aug 26, 2003 2:58 pm

Does anyone know of a mac osx or ox9 spectrum analyzer?

Cheers,
S3

giles117 · Post by **giles117** » Tue Aug 26, 2003 11:54 pm

Spectrafoo

http://www.mhlabs.com/products/spectrafoo.html

Bryan Giles

s3 · Post by s3 » Sun Sep 14, 2003 7:23 am

I have a new question on this topic...

In another thread, that I can't find at the moment, somebody had a graph that was output from whatever software they were using to test the freq response of their room. That person explained how they recorded the pink noise test tones back into their their DAW to do the analysis.

My question is..Can someone please explain the exact process of doing the measurements this way or post a link where it's explained in detail? I have been to both John and Ethans site already and I didn't see it in either place. If I missed it please forgive my mistake.

Cheers,
S3

knightfly · Post by **knightfly** » Sun Sep 14, 2003 10:01 am

I'm running too close to work time to look for that thread - here's a few companies with acoustic software, sort of in order of cost - check out ETF, it's a real bargain for what you get -

http://www.etfacoustic.com/

http://www.mclink.it/com/audiomatica/clioeng.htm

http://www.cara.de/ENU/index.html

ETF starts at $150 if you use your own hardware, it allows "profiling" so your hardware can be made to look "flat" , etc - good study pages in demo room too... Steve

Ethan Winer · Post by **Ethan Winer** » Mon Sep 15, 2003 12:49 am

S3,

> Can someone please explain the exact process of doing the measurements this way <

I don't recall if my Acoustics FAQ has the exact steps. Here's what I've done:

Play pink noise fairly loudly in mono through both of your speakers. Put a high quality omnidirectional condenser mike at the mix position. Record a minute or so of the noise to a Wave file, being careful not to make any noise yourself by moving around. Then you can analyze the Wave file in an audio program. I've used SoundForge, but there are others that also offer a spectrum analyzer. Or you can get a spectrum analyzer plug-in.

I have to point out that conventional 1/3 octave pink noise analysis leaves a lot to be desired. The main problem is that a third of an octave is far too coarse to see what's really happening. A typical room has many peaks and nulls throughout the bass range, and it's common for both a peak and its adjacent null to both fall within the same 1/3 octave band. So the average reading for the entire band is nice and flat, even though the response really varies by 15 or more dB!

--Ethan

s3 · Post by s3 » Mon Sep 15, 2003 5:06 am

Ah crap! the light just went on! I hadn't listened to my test tone cd yet. I just assumed (first mistake) that it had individual tones at every 3rd octave. I didn't realize it was just one sound that encompassed the entire freq range. Duh... That's why I couldn't understand how you were getting to the graph if you had to record so many individual wav files for the program to analyze. My bad....Thank you both for your help. I will have results later today.

Cheers,
S3

s3 · Post by s3 » Mon Sep 15, 2003 5:10 am

Um..that's 1/3 of an octave. Whether I have the terminology right is still debateable.

Cheers,
S3

barefoot · Post by **barefoot** » Tue Sep 16, 2003 8:05 am

S3,

Do you have a wave editor program like Sound Forge or Wavelab?

Thomas

s3 · Post by s3 » Tue Sep 16, 2003 2:39 pm

I bought the spectrafoo thing that was mentioned earlier in the post (Pricey). I have Mac. I just realized that I don't have test tones at individual freq for use with my SPL meter. Any suggestions on a useful test cd for these types of measurements?

Thanks,
S3

giles117 · Post by **giles117** » Tue Sep 16, 2003 6:56 pm

http://www.testdisc.umsebiz.com/

I Used these a few years back. Pretty good.

FlatPink for Pink Noise

Bryan Giles

The Other thing you can use is....

http://www.nt-instruments.com/flash_vie ... PageId=465

s3 · Post by s3 » Wed Sep 17, 2003 3:32 am

Thanks! I may get those test discs today!

The NT-Instruments thing I could never get to work on my mac. What browser did you get it to work in?

Cheers,
S3

giles117 · Post by **giles117** » Wed Sep 17, 2003 9:01 am

I was able to get it to work only with Explorer.

I know I Know, I sent Apple in a bug report to get it fixed for Safari

Oh well, gotta keep that program around for 1 reason.

Bryan Giles

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"Noising" a room?

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