The cornerless room

lowdbrent · Post by **lowdbrent** » Fri Jun 13, 2003 7:48 am

I was wondering if anyone has trued and published data on the following.

The corners of a room are the places where standing waves and bass build up occur right? Why not build a room without any corners? Build a room within a room, but do not cover the corners of the vertical or hoizontal boundaires with wall board. All corner areas are bass traps.

Another advantage would be that a 14 x 19 room would be a true 14 x 19 room. And in a room this small, space is a premium.

I suppose that the real wall traps could be done in the same fahion. They would be flush with the room's wall, saving space.

Post by **John Sayers** » Fri Jun 13, 2003 9:48 am

I was wondering if anyone has trued and published data on the following.

sorry - no one has done the maths on that yet. Yes why not get rid of the corners - that's whatcorner traps are for.

cheers
john

Eric_Desart · Post by **Eric_Desart** » Wed Jun 18, 2003 6:39 pm

Hello John,

Congratulations with your nice forum.

To lowdbrent.

It's a wrong conclusion that standing waves build up in the corners.
ANY room shape has room modes.
There are ca 11 regular shapes which can be calculated analytically (as e.g. a circle) all the other shapes must be calculated numerically.

Look at the Chladni applet:
http://www.phy.davidson.edu/StuHome/jim ... modes.html
or the modes in a guitar bottom:
http://www.phys.unsw.edu.au/~jw/guitar/ ... _engl.html.

While this are modes in plates, the basic principle is identical to room modes in a 3-dimensional space (reverse nodes and antinodes). Note at the guitar bottom the lines are the nulls (nodes of the modes).

But with FEM (Finite Element Analysis Method) or BEM (Boundary element Method) software you can calculate and simulate the modal behavior of any room shape, also complete irregular ones.

So removing corners in the basic design has no sense, and often they are a great spot to build bastraps or very low extending broadband absorbers.
As such corners are no limitation but a help.

And for geometrical acoustics (frequency > 2 * Schroeder frequency) such rounded corners are mainly a problem, seldom a solution.

Eric

Eric_Desart · Post by **Eric_Desart** » Wed Jun 18, 2003 6:45 pm

To explain the last sentence:

A rounded corner acts as a reverse diffuser focussing the sound.

Eric

Post by **John Sayers** » Wed Jun 18, 2003 8:46 pm

Welcome to the site Eric - I'm so glad you've come. Please feel free to offer your extensive knowledge to this site, it would be greatly appreciated - my offer to moderate the acoustics forum still stands and it's much easier to operate and gives better access to pics than your current forum

and like Yahoo - it's free

cheers
john

Eric_Desart · Post by **Eric_Desart** » Wed Jun 18, 2003 9:15 pm

Hello John,

Really thanks for the welcome.
I do agree your site looks nicer than Yahoo.

But, please hope you understand, I like to be loyal.
Don't mind my English. You know I'm Dutch.

But I think about your suggestion for which my thanks.

Very kind regards.
Eric.

Still like your pages on SAE

Post by **John Sayers** » Wed Jun 18, 2003 9:23 pm

But I think about your suggestion for which my thanks.

please think about it Eric - there's a group of us who would really appreciate your input to this site. right guys?

cheers
john

knightfly · Post by **knightfly** » Thu Jun 19, 2003 9:19 am

Definitely got MY vote - Eric, your posts on yahoo are among the FEW I actually pay SERIOUS attention to - although I've yet to post a question there, I do have a few for you (if you feel like sticking around for a while)

Again, a hearty welcome (whether you come to work or play :=) Steve

will · Post by **will** » Wed Jun 25, 2003 3:15 am

Erik,

heel hartelijk dank voor je bijdragen.

sorry, folks ...
[dutch mode off!]

John and everybody, i just couldn't resist a reply in dutch to Eric.
Thanks very much for this great service.
I'm still absorbing (!) all the info, before i order the rockwool.

groeten/cheers
will

lowdbrent · Post by **lowdbrent** » Thu Jun 26, 2003 1:13 pm

You have the wrong impression. I am not talking about rounding out the corners. I am talking about trapping the corners. The traps just don't take up the corner space in the room.

zodprod · Post by **zodprod** » Tue Aug 19, 2003 3:58 pm

Erik,

It would be fascinating and insightful to rerun that experiment of vibrating plates with the shape of my control room.

Anytime you want to set it up I can send you dimensions.

Xspringe · Post by **Xspringe** » Thu Aug 21, 2003 3:25 am

will wrote:Erik,

heel hartelijk dank voor je bijdragen.

En namens mij ook

[/dutch mode]