Tweak3D.net - 3D Audio: How It Works

Posted: April 10, 2000
Written by: Tuan "Solace" Nguyen

Introduction

Once in a while, technological breakthroughs come by and astound society. And surround sound is no exception. You've probably experienced surround sound in one form or another. If not, at least stereo sound. If your PC isn't primed for 3D audio, your hearing is missing the big leagues. And if you haven't heard of such technologies as Dolby Digital, A3D, EAX, or S3D, then hopefully this article will spark some needed interest. We'll tell you how surround sound and 3D audio works.

Wet Willy

Quite often you'll see a little button on your speakers with the print "3D Audio" or "Surround Sound" used to enable a '3D effect' on your sound output but to your dismay, the sound is either garbled up, loses frequency response or doesn't do anything. The technical name for this effect is called "Expanded Stereo" and it is nowhere near true "3D" audio. The technique we're discussing today is called "Positional 3D Audio". A system capable of this should be able to place sounds in the space around you; above, below, and behind you.

In a movie, having 3D sound isn't as significant as it is on the PC. This is because we want the sound to interact with what we're doing. We want to be able to experience sound as it is when we hear it in real life. For example, when a Ferrari drives by you in Need For Speed IV, you want to be able to hear it's trajectory. And the sound that the engine makes when it gets closer to you changes in detail as it does in volume. This is the main difference between true interactive positional 3D audio and surround sound which just immerses the listener in an audio environment but is less conscious of sound placement.

Surround sound was first introduced for featured films in theaters because the technology was too expensive for home use. Then eventually it slid down into home entertainment systems and in recent years, computers.

Types of Audio Enhancements

There are three methods that companies and developers use to enhance sound in a game or a feature film. Being almost completely different from one another, all three will still enhance your listening experience. And some might even ruin it.

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