Tweak3D.net - 3D Audio: How It Works

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

Currently the most regarded APIs are Aureal’s A3D and Creative’s EAX. Although they are different technologies for different purposes, EAX is more widely used than A3D. This is because there is already DS3D underneath EAX and while not as good as A3D, it is already there and therefore much easier to program for than A3D. All the programmers have to do is to program for DS3D, and choose the appropriate EAX preset and everything is set. In A3D, they have to program for both DS3D and on top of that program for A3D’s wavetracing technology. But, if effort is put into designing for A3D, the end result according to majority, sound better than EAX enabled DS3D.

I3DL2

You may notice how we kept I3DL2 technology for last. This is because it is neither a surround technology, 3D positioning, or reverb technology. Developed by the Interactive Audio Special Interest Group (IA-SIG), I3DL2 (Interactive 3D Audio Rendering Guidelines) Level 2 is a set of minimum acceptable 3D audio features that all platforms should have. Aureal, Creative and Sensaura and other companies contributed to this standard. You can think of I3DL2 as the DirectX of sound. Currently, Level 3 is being developed and may include Creative’s EAX morphing.

Conclusion

Which technology should you choose? Well, you must consider the following factors. Everything lies on top of DS3D, which in itself does not sound very good because it is missing a lot of effects. This is where the other APIs come into play. But whichever one you end up choosing, you should definitely consider the number of speakers you’ll be using. You’ll also want to check on the games that each API supports. If you are going for accuracy and realistic positional 3D audio, consider soundcards based on Aureal’s Vortex2 or ESS’s Canyon 3D technology. If you’re planning to use more than 2 satellites, then Sensaura is the best choice. If you’re only using two front speakers, then A3D is the best.

While Creative Lab’s Sound Blaster Live! series of soundcards don’t really offer any proprietary 3D acceleration, it does accelerate DS3D with its own EAX API, enhancing the base DS3D streams. And while its approach is not as accurate as A3D or Sensaura, the effect does "immerse" you. However, the majority of gamers say that nothing beats A3D. The Live! cards do offer a lot more to the table as well, such as an abundant number of hardware reverb effects and it is designed for the musician as well, while Sensaura and A3D is directed more toward games.

One important thing to note is that Creative is working with Microsoft to incorporate EAX into DirectX. If this does happen, then EAX will be available to any soundcard that is compatible with DirectX, providing one less reason to buy Creative’s card.

Test each technology out and see which one you like best. We can soak you up with all the information there is about these technologies, but the end choice is really up to you and your ears.

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