Saturday, May 23, 2009

Room Acoustics & Home Cinema Rooms

Room acoustics play a huge role in creating a successful home cinema. The best home cinema hardware in the world will fail to perform at its best in a badly designed room.

The main issue in a home cinema tends to be excessive reverberation time - this is the time taken for a sound from a speaker to decay by 60dB below its original level - i.e. the amount of time it takes for a sound to dissipate in the room.

If you can imagine standing in a completely empty room with hard floors and ceilings and clapping your hands, the sound will echo for quite some time and therefore take a long time to decay (it reflects off the walls and floor). Now imagine standing in a carpeted bedroom and clapping your hands, the sound would not echo as much and disappear quite quickly (the bed and the carpet would absorb some of the sound). The bedroom has a lower reverberation time than the original room.

In a home cinema it is generally good to have a shorter reverberation time as if the reverberation time of one syllable overlaps the other it can be difficult to make out speech. The same thing happens with sound from the surround sound speakers - one effect overlaps another resulting in a muddle of sound.

Home Cinema Treatments

There are several ways to treat excessive reverberation time - changing the shape of the room is one. Imagine a square box, a wave comes out of the speaker hits the back wall and comes back 180 degrees on itself - muddled sound. Now imagine a complex shape like Octagon, some waves will still bounce back at 180 degrees but the majority will bounce off in different directions - the sound still exists but all the bouncing will reduce its energy quite quickly (and therefore volume) and keep the sounds distinct.

The other way to treat excessive reverberation is to absorb the wave - acoustic panels consist of acoustic substrate finished in fabric. This tends to be the most practical way to improve the sound in your room and the finishing fabric can be almost any design - improving aesthetics at the same time as the sound. Manufacturers such as Cineak and Cinematech have products available in a variety of sizes and shapes to cater for most situations.

Written by: Dave Chester

Custom Controls

http://www.CustomControls.co.uk

Custom Control & Entertainment Solutions - Home Cinema, Multi-Room Audio Video, Home Automation & Lighting Control. Premier Dealers for Crestron, Kaleidescape, Lutron and Bowers & Wilkins.

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