Acoustics and rooms

[cpl_crud]

Okay. Let me start out by saying that I'm not intending to set up a professional studio in a garage, or something equally as silly. Although my experience isn't as vast as a lot of forum members, I do actually know what I'm doing.
I also have a physics degree, which is where I'm heading with this post.
When designing a room for recording, what are the acoustic paramaters that you're looking for? e.g. absorbtion/transimission of the walls, primary lengths, baffles, reflectors and the like.
I've worked in some pretty neato rooms for concerts (like the new Recital Hall in Sydney), and I've always wondered what combination of properites makes a "good" recording space (obviously in a concert space, you want a room that sounds like a hall, and allows the sound to reach everyone in the audience, but minimising reverb and feedback where required).
Does this make sense to anyone? Is there a set of properties that you're looking for? Or do most people just design thier room on the basis of what's available?

Thanks guys.

 

[Ethan Winer]

CP,

> Is there a set of properties that you're looking for? <

Yes! Especially for small rooms as opposed to concert halls. These are very different and have very different criteria.

One goal in small rooms is to optimize the ratio of length, width, and height. Another is to treat the room so the decay time is more or less uniform at different frequencies. For a good introduction to these concepts see the Acoustics FAQ, second in the list on my Articles page:

www.ethanwiner.com/articles.html

Read the sections that explain room modes, and also the sidebar that explains the ModeCalc program (Windows) you can download. There's a lot of other information too about absorption, diffusion, bass traps, and so forth.

--Ethan

 

[spoonie g]

ethan, you are truly a resource of information and an all-round helpful person.