Hi Shezan, if you post a question in one forum it's considered bad form to then re-ask the same question in another forum, that's referred to as "double posting". No biggie by me but I just thought I'd share that. 8-)

There are a couple of different approaches to this (not professional but good for a project studio, acoustic people please don't kill me for my poor language...):

Clap your hands and see if you have a slap echo (TRRRR) this is bad, you need diffusion (different shaped objects, search on google for "acoustic diffusion"...) in the room and diffusion goes in the back because in the front you will need absorption.

Listen to music that you know very well and you have listend to in good rooms. If you hear a lot of bass you need bass traps (search on google for "bass trap").

If you have any sort of digital recording program and an omni mic you can record white and pink noise (I'm still trying to understand witch one, maybe someone can help for this) from the place where you are mixing. Place the omni on your seat where your head is. Process the sound into a freqency analyzer and see where you have peaks. The ideal situation is that everything is flat.

Again, sorry for making it simple, I'm not sure how much shezan knows...

Hope that helps. Bas.

baslotto wrote: If you have any sort of digital recording program and an omni mic you can record white and pink noise (I'm still trying to understand witch one, maybe someone can help for this)

White noise is equal sound energy per Hz. Pink noise is equal sound energy per octave, which is how we hear things, so pink noise sounds flat, and white noise sounds awfully high frequency weighted, not much use. Pink noise is the best acoustic test source.

Thanks David, I knew what they are and I know pink noise would be more appropriate but for this kind of test. I also read something about using white noise as part of the test, I can't remember how. Is it true or I'm making this up? :)

Sometimes white noise is helpful if you are processing the measurements with an FFT and the data is bucketed (bad term, but I can't think of another at the moment) into equal Hz elements instead of by octaves. If you use pink noise and get a very tilted measruement (bottom to top), try the measurement again with white noise.

They are both valid measurements, but it is easier to interpret the results if you use the one that matches your measuring technique.

Michael

True, white noise should be used for narrow band linear FFT analysis, but most FFT analysers also have log frequency functions, and these should be used for testing of audio or acoustic parameters when doing broad band full spectrum tests.

If you only have white noise, you will blow your tweeters up trying to get enough SN energy for a valid test at low frequencies. Log frequency driving and measurement is tha answer.

Swept measurements, ie not broad band all freq at once, is another testing method that gets excellent energy excitation without the HF crunch.

I am still hoping to arrange some swept sine impulse response measurements in our wonderful theatre to use in SIR, but time, access, and permission to drive the room with 120dB at all frequencies are still a problem. The light fittings will probably all fall out. :)

All the RTAs I've seen used to tune rooms incorporated a sweep of pink noise. SIR rules.

Calgary wrote: All the RTAs I've seen used to tune rooms incorporated a sweep of pink noise.

The best of both worlds, indeed.

guys thanx alot for your information... i really knew about the white noise and pink noise but i never thought of using it that way...this place has always been a good help for me... i was already in plan to buy a multi pattern mic so i m definitly gonna start trying things like you guys mentioned...thanx again