How do you make something that improves the acoustics of an auditorium?

August 9, 2008 3:04 PM

Can anyone offer me some suggestions for how to make a relatively inexpensive sound trap (i.e. like those echo reducers that large auditoriums have). Info about materials, shapes, etc. would be helpful.

I'm a science teacher trying to make our school's auditorium more functional by reducing the echos which make it hard to understand most performances. I plan on writing a grant to cover most of the cost but I really need help figuring out what and how I would make these sound traps.

posted by n8stew to Science & Nature (3 answers total)

This is a great resource on acoustic treatments. I'd say what you need is some diffusers, which don't absorb sound but rather scatter it in different directions, eliminating the direct reflections that sound like echoes. Bookshelves with a variety of shelf spacings are a simple and cheap way to accomplish this.
posted by waxboy at 3:44 PM on August 9, 2008

The Master Handbook of Acoustics by F. Alton Everett is the bible.
posted by rhizome at 4:08 PM on August 9, 2008

Second waxboy's recommendation of Ethan Winer's pages. There's lots of good info at AVS Forum and the Studiotips forums as well (albeit aimed a slightly different needs than yours, but there's an awful lot of overlap; it's a lot harder to sort through than just reading Ethan's pages, though, so start there).

I built a set of rigid fiberglass-based absorbers for my home theatre room (70 square feet of 2"-thick panels made of Owens Corning 703 set in wood frames and covered in acoustically-transparent fabric), and a pair of "superchunk" style bass traps in the corners (stacked triangles of OC703, 24" x 4', also in a minimal wood frame), and these turned a very echo-y room into something that sounds quite nice. Granted, the needs and constraints of an auditorium are different from those of a home theatre, so think carefully about what exactly the problem is and whether you need absorbers, diffusers, bass traps, or what -- and how much (you don't want it to sound dead) -- but I'm sure you can some up with a reasonable DIY approach that can make the space sound much better.
posted by SeanCier at 10:07 PM on August 9, 2008