Warning, we’re going to attack your left-brain tendencies for a minute.

Most of us like symmetry. Mirror images. Parallel lines. Socks and shoes that match. Twins. Wow, that got inappropriate in a hurry! Sorry. Unfortunately, symmetry in the placement of acoustical panels in your listening room is likely the wrong approach. The only symmetry we want to hear is what is coming directly out of your left/right speakers. What bounces off your left and right side walls should actually be un-correlated (asymmetrical) so that your brain can identify it as non-essential reflections.

Your listening room for movies or music is directional.  In front of you is the performance - be it what’s on-screen or, with music, an image floating in space. The space that you face is the experience…the source. The idea is to minimize the sound field distortions and the effect your room is imposing on the frequency response.  

As they say in Star Trek, we want to create a “Neutral Zone” for your sonics. This big picture stuff is like purple food for your right-brain, right?

We approach the creation of this neutral zone by starting with the side walls toward the front of the room. Typically, there are parallel walls left and right of the main listening area - smooth, hard surfaces where sound ping-pongs back and forth (technically called slap or flutter echoes). They create little spikes in the time domain, alter the frequency response, and distort or blur the sonic image.  We minimize this effect by applying absorbers on one of the two surfaces that make up the slap echo. Alternate the absorber placement left and right of the center listening area, leaving space for 2D hemidisc diffusers (like Sonitus Fourfusor or Sharpfusor) or a combination diffuser/absorbers (like the Sonitus 6-Strip).

This “interleaving” of components gives the room balance and comfort. Why not just use absorbers? There is a spatial penalty for using too many absorbers. It will soak up too much energy, making your room sound like you're hiding under the covers - great for ditching the boogey-man, but not for your listening room. Continue this interleaving of absorbers and diffusers until you just get past the central listening area.

What goes on after the sound flies by your listening spot at the speed of sound (1,128 ft./second at sea level) is a different matter. We want yesterday’s news to be scattered randomly. For this we continue to interleave diffusers with absorbers on the side walls, but now we’re going to use those crazy-cool looking 3D hemisphere diffusers rather than 2D. The 3D diffusers randomize the reflections and reduce the ear’s ability to focus on distracting point source reflections.

This creates a spacious sonic bloom which gives the room a natural and comfortable sense and enhances the surround effect for home theaters.  

For the back wall (if you have one), we suggest absorbers directly behind the listener's happy spot to minimize slap echo. Flank them with more 3D diffusers towards the room’s corners (not in the corners).  All you need now is air freshener.

Sure, we glossed over some details and left out bass traps in the corners of the room (where low frequencies congregate and socialize), clouds for the ceiling first reflections, and front wall bass absorbers (like Sonitus Decosorbers) between/behind the speakers and/or screen. The object of this article is to prime the pump - get you thinking strategically and conversationally about the project ahead. It should also add value and show our experience and thinking behind the systems we recommend. We love to talk about this stuff, so send us a postcard, drop us a line at help@sonitususa.com, or call 1-800-497-2087 and ask for Anthony.

Footnote: It should be obvious that those interested in planning acoustical treatments for a recording space that’s used for tracking acoustic instruments like drum kits and oboes can sit this one out. However, the learning does apply to control rooms. In any case, call us to chat about how you plan to use your room and to get our take-it-to-the-bank recommendations!

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