Computer speakers glossary

Here you'll find some common terminology that can sometimes confuse (and is often used to confuse) people new to the world of computer speakers.

2.1 Speaker system

Basically stereo plus a subwoofer, this is a format that expands on the concept of stereo speakers. It adds a third speaker, usually a remote powered sub woofer that reproduces only the lowest frequencies.

Dolby Surround

The first surround technology developed based on commercial theatre system. The only system exclusively supporting this format will be second hand. It consists of the playback of three channels—stereo left and right and a mono surround channel with a limited frequency response that would feed speakers behind the listener. No center channel for speech.

Dolby Surround Prologic

Provides stereo left and right, mono surrounds, and mono center channel. The advantage of the center channel is that vocal frequencies are reproduced in a speaker ideally placed at the visual source, localizing the vocals in a movie to the actual faces on the screen.

Dolby Digital

This technology is centered around the 5.1 Surround standard. It consists of six discrete channels- stereo left and right front, stereo left and right surrounds, center channel, and the low frequency sub woofer channel.

A3D

Aureal’s surround sound coding product named A3D. Basically virtual surround designed for headphones. Uses clever techniques that basically fool the brain into positioning sound locations, very effective.

Creative Labs EAX

EAX, or Environmental Audio Extensions, is based on algorithms developed by Creative Labs that have been implemented in their sound cards and speakers systems. It is based in a 4.1 surround sound concept, absent the center channel for vocal range directivity. There's more information in our surround sound computer speakers guide.

DTS

DTS, for Digital Theater System, was introduced by Steven Spielberg with the release of Jurassic Park in 1993. So far, this standard applies more to the big screen than to the private home. It, too, is 5.1, with sound coded over six channels like it is in Dolby Digital. However, while DTS quality is undeniable, and even a bit better than Dolby, remember no movie comes out in DTS alone and Dolby is considered a digital sound standard while DTS is not.

The main feature of DTS is that its coding system favors sound quality over disk space. So a DTS sound track codes in 20 bits (specifications allow for coding in 16, 18, 20 and 24 bits) instead of the 16, 18 or 20 bits with Dolby. Compression uses a dynamic process where the compression rate varies with the amount of sound to encode. This rate ranges from 1:1 to 40:1, and generally results in better sound quality than Dolby Digital with an average rate of 1.5 Mbps.

RMS power output (watts)

This is the only power output rating worth comparing. RMS stands for the root mean square. This would be the area under the line if an amplifiers power was plotted against time. Basically this is the maximum SUSTAINABLE power output of the amplifier. PMPO or burst power output measurements are not accurate since most amplifiers can produce 1000s of watts for a few milliseconds while only the very best can sustain an output of a few 100 watts RMS.

THX

THX certified speakers are guaranteed to produce a good frequency response for movies and games.