What are the best materials for optimizing acoustics in a home theatre?

Commercially built diffusers, irregularly shaped furniture, and acoustically transparent cloth can be used to scatter sounds and improve the overall acoustics of a home theatre room.

How can I test if a cloth is acoustically transparent?

You can hold a large sample of the cloth in front of a speaker playing pink noise to see if you can move the cloth without hearing a difference in sound.

How can I address excessive use of absorptive materials in a home theatre room?

While absorptive materials can be powerful, it's important to balance reflectivity and diffusion for optimal acoustics in a home theatre room.

Excessive Use Of Absorptive Materials

Commercially built diffusers are available but large bookcases and irregularly shaped furniture will also serve the same purpose. They reflect sounds in a highly randomized way which effectively “scatters” the sound in all directions. Place the diffuser where you would otherwise place the absorptive material (using the “mirror trick”), to break up the first early reflections and scatter them randomly throughout the room.

Commercially available fiberglass, foam and diffusion panels may not be aesthetically acceptable in many installations, particularly when the home theatre room serves multi- ple purposes. All of these materials can be covered with acoustically-transparent cloth for design considerations. It is important that the cloth be acoustically transparent, however, or else the effectiveness of the absorptive material will be greatly reduced. The simplest test for this is to hold a large sample of the cloth in front of a speaker playing the pink noise found in Chapter 6 of the WOW! laserdisc. If you can move the cloth in front of the speaker without hearing a difference, you are all set.

Large expanses of glass can be challenging. They reflect mids and highs but often pass bass through almost as though they didn’t exist. The result is a characteristically bright, rough sound which can be difficult to correct electronically. The best treatment is generally the heaviest insulated drapes which can be found. (Incidentally, these serve double duty, controlling light which might otherwise fall on the screen.)

The materials just discussed are ineffective at lower frequencies. See the discussion on Standing Waves for more information about treating environments with low frequen- cy response problems.