Floyd Toole in Sound Reproduction recommends using a diffuser on the ceiling that should scatter sounds from front loudspeakers that would normally be reflected to the head locations of listeners. He suggests an engineered diffuser that is designed to scatter sounds toward the sides of the room.

Has this problem been solved? If not, how would I go about designing a diffuser that would direct ceiling reflections originating from the front of the room towards the edges of the room instead of the center?

  • Room is going to be roughly 18'x12'x10'H and is not yet built. Walls will be treated with appropriate diffusers and absorbers and covered with acoustically transparent fabric. Speakers are in recommended 7.1 locations. Aug 13 '17 at 0:05
  • Most of this information shouldn't be pertinent. I'm asking about diffusers that are specifically designed to direct sounds originating from the front loudspeakers and reflected off the ceiling to the outer walls as described by Toole. Thanks! Aug 13 '17 at 0:06
  • Voting to close. This is an acoustics question and is probably more appropriately placed on the physics stackexchange site.
    – Mark
    Aug 13 '17 at 14:21
  • @Mark is there a meta post that shows acoustics as off topic? Why is there a tag if it's off topic? Aug 13 '17 at 14:52
  • I don't think this is explicitly off topic - if you want an equation which details exact dimensions and angles etc., that would feel like Physics, but there are relevant answers here, ass you can see from @schizo's post.
    – Rory Alsop
    Aug 14 '17 at 13:28

A diffuser is used to scatter sound waves unevenly so the surface needs to be also very uneven. So you need a mildly reflective material such as wood or cork cut out so that it has edges and crevices of different sizes, angles and shapes. This will cause the round or flat (depends if we're talking near of far field and consequently the size and shape of the room and speaker placement) to break into frequency components that are reflected to different directions. As a result, you won't be able to hear individual reflections as easily.

It also breaks the symmetries of the room to a certain degree, especially if it's curved and placed between the ceiling and the wall behind the listening position, and thus stops some standing waves.

Unfortunately, I can't give you an answer in terms of formulas or certain designs for two reasons. a) I don't have enough information (like the purpose of this room, listening position, internal shape and the materials inside it) and b) I'm quite rusty with acoustics and I wouldn't want to tell you something that isn't correct. It's also the kind of thing that is done with specialized software rather than trying to make approximations using pen and paper.

There are companies that specialize in acoustics and they should have the software to suggest a certain shape/construction.

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