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The Acoustic Foundation

Acoustics play a vital role in the quality of a home theater.

I have been asked a few times recently if acoustic design work for home theaters is important, and, furthermore, at what point that design work should take place.

Acoustics play a vital role in the sound of a home theater. Consider this: In a typical listening room, when you sit 12 feet from the front speakers, you are actually listening to more reflected sound energy from the room than direct sound energy from the speakers. Thus, the rooms acoustic “thumbprint” affects more than 50 percent of the sound that you hear.

The field of acoustics as applied to home theaters actually comprises several areas. First, there is sound isolation. The room should be completely isolated from the residential environment around it so that loud and distracting sound leaking out of the theater does not bother everyone in the house. Second, the room should be totally quiet inside. No fans, no street noise and no vibrations should be heard, or you may miss subtle elements of a film or song. Remember that the latest audio formats theoretically provide up to 144 dB of dynamic range, so you had better have your room completely silent if you want to hear the full range of sounds that those new-fangled high-definition formats offer. Also, noises that turn on and off, like a ventilation unit, can distract listeners from a movie, which is counter-productive to what we are trying to do: immerse our customers in an entertainment experience that is so optimized that they are transported into the action.

Third, a home theaters bass resonances should be minimized. If they arent, then the tight, punchy bass that we have come to expect from dynamic digital tracks turns into a thick mush for which no one in their right mind would pay money to listen.

Fourth, the sound reflections within the room should be controlled through careful and strategic use of absorption and diffusion techniques. Controlling reflections will improve dialog clarity and musical articulation, while solidifying phantom images and opening the soundstage. Ultimately, the multiple speakers of a surround system will integrate better in a room with proper acoustical treatments.

Acoustical treatment layout is sometimes thought to belong in the domain of experiential art. In fact, it isnt black art at all, but because scientific findings in this area are only very recent, many people prefer to relegate it to the field of mysticism. Thanks to recent research in the areas of psycho-acoustics, acousticians are now know able to predict optimal reflection decay times, scattering patterns that produce the most pleasing sound and thresholds of audibility for discrete reflections. You can put all of this information to good use and design in a layout that will work from the word go.

There are also very cool acoustical modeling programs, such as Ulysses form IFB Soft, that allow you to build up a 3D CAD version of a room on a computer, then place speakers in it and determine all the relevant reflection paths. You can optimize the treatment locations and ultimately listen to a .wav file processed through the programs DSP capabilities. Customers will just love being able to hear their rooms before theyre actually built.

At any rate, the good news for you is that materials, services and products are all available to help you and your projects achieve acoustic nirvana. You can make a good profit margin at the same time as youre making your customers grin from ear to ear.

A high-end home theater audiophile recently called up his dealer, who had contracted my firm to perform his acoustic design, and enthusiastically claimed that the treatments that we specified had done more to improve the sound of his system than any upgrade he had tried in the last five years, by ten-fold. Think of it. You can provide real, audible, value to your customers by offering acoustic design services and products, while separating yourself from the vast masses of dealers talking techno-babble. Acoustic treatments require no batteries, dont break down and require no programming. Can you think of an easier way to add value and profit margin on a project?