measuring acoustic response of the room...

[Branimir]

greetings everyone, recently i've stumbled onto this forum and it's very very good! it's very informative and friendly!

heh..
well, i've been sound treating (is that the term) my band's practice room and looks like i'll be doing some diy corner bass traps to reduce the boomy effect... i came to the question of the acoustic response of the room...

is there anyway to measure the reflections, echoes, reverbs to determine what kind of treatment the room needs. for example to flaten the freq. response of the room and still not to make a really dead room...

there is a guy in the city where i live who has 5 practice spaces wich he lends on 2 hours and stuff like that, you know, per hour rented practice space with drums in it, amps and pa... we (the band) used his services and despite his really quality drums, quality amps and a good pa the rooms always sounded kind dull and lifeless.

we had a garage before and it was much much pleasant to play in it and the sound was more "natural"..

2 weeks ago the same guy (he had 3 practice rooms) began to build 2 more... since i knew him from.. like when he first started the rent bussines i asked him how he isolates the rooms and all that stuff...
and the final spot was the carpet on the walls and ceilings...

few days ago i found out that carpeting will make the room dead on the higher frequencies... so it accured to me that he overtreated the room in order to make it better, heh..

anyways there must be a way to dose up the types of treatment, right? i mean, if there's higher frequency reflections of the walls, a bit of carpet would do good, woudn't it?
so, is there any way to "measure" the room and then to apply sound treatment as needed...

i'm an electronic tehnician so use any tehnical terms i will understand them.

sorry for my messy english, greets from Croatia!

[Ethan Winer]

Branimir,

> is there anyway to measure the reflections, echoes, reverbs to determine what kind of treatment the room needs. <

Yes, but it's not as valuable as you might think. No matter what you measure the solution is always the same - broadband absorption that's effective to as low a frequency as possible. Have a look at the Acoustics FAQ, second in the list on my Articles page:

www.ethanwiner.com/articles.html

Also see my recent article from Electronic Musician magazine, linked from the Articles page on my company's web site:

www.realtraps.com/articles.htm

If you really do want to measure the room - and I'm not saying you shouldn't! - look into the ETF software from www.acoustisoft.com.

--Ethan

[lovecow]

Brainmir,

You might also check out Audio Toolbox, SMAART and TEF. If you understand technical terms, then what you want is an analyzer that will perform FFTs. Preferably in real-time, but post-processing an impulse response is completely fine. All of the above and ETF have single-channel and/or dual-channel FFT capabilities - or some hybrid thereof.

IMO, ETF is the least expensive and is quite easy to use. (A lot of the graphs you will want to look at are preset buttons in the GUI.) Audio Toolbox is the best bang for the buck as you get way more than just acoustical tools. SMAART and TEF are probably the most dedicated systems for room acoustics. TEF in particular is very versatile and probably the most accurate. However, both of these are going to cost a lot more to get going that ETF or Audio Toolbox.

My $0.02.

Best regards,

Jeff D. Szymanski
Chief Acoustical Engineer
Auralex Acoustics, Inc.