Room Dimensions

Discussion in 'Archived Threads 2001-2004' started by Bob_M, Dec 27, 2001.

  1. Bob_M

    Bob_M Stunt Coordinator

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    Hi All,

    I am planning an addtion to my house which will include a family room house the Stereo equipment. The question is what inside dimension should I make the room. I am looking at something around 15x20. Any rule of thumbs I can use for dimensions. An explanation of why a particular set of dimensions would offer poor acoustic performance would be helpfull too.

    Thanks

    Bob
     
  2. Cees Alons

    Cees Alons Moderator
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    Cees Alons
    Hello Bob,
    The main problem in a room are standing waves. If two opposite walls are exactly parallel and a bit reflective (for sound), there are some frequencies at which the distance between those walls are an exact (integer) multiple of the wavelength. Those frequencies will sound louder than they should.
    You can avoid that by using deadening materials (curtains, furniture, carpet, etc.) and by avoiding too much parallel walls (don't forget the floor and the ceiling!). Also try to introduce some irregularities in the shape of the room.
    Now another problem arises if the dimensions of the room are a simple (integer) ratio of each other, like 2:3 or 4:5, or so (worst would be a perfect cube [​IMG]). In that case the waves that are favoured by one set of walls are also favoured by another set - or else their harmonics are.
    To avoid this, try a non-rational ratio ([​IMG]) for your length:width:height. And deaden.
    Cees
     
  3. Bob_M

    Bob_M Stunt Coordinator

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    Thanks Cees that makes sense. Looks like a good prime number dimension would work out, say 13x23? The new room will have a cathedral ceiling so I would assume this would be a good thing since the floor and ceiling are not in parallel?

    Bob
     
  4. Cees Alons

    Cees Alons Moderator
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    Yes, Bob, I think 13:23 is already reasonable, although they're still integer numbers. Having a square root in one of the ratios is even better, e.g 1:sqr(3), which is close to your number (a famous one is the "golden cut", which is 2 : (sqr(5)+1) = 1:1.618033989).

    And don't forget the dampening!

    Yes, a ceiling that's not parallel to the floor is great for your accoustics!

    Cees
     

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