3D Audio

Of course, no sound card review these days is complete without a discussion of 3D Audio. I'd like to preface all of this by stating that I was probably the world's biggest skeptic of 3D sound. I had no desire to pay $199 for the original PCI Monster Sound in early 1997, even though I am a notorious early adopter. I thought 3D sound was just another marketing scam to get people to drop money for new sound cards.

But when Diamond introduced the $99 M80 version of the Monster Sound, I was intrigued. PCI audio is probably a good thing, I thought, even if it does have to carry the questionable marketing burden of "3D Audio". So I dutifully ponied up my $99 and brought it home to try. Expecting the worst, I fired up the first 3D audio demo that came with the card.

Boy, were my ears opened. Aureal models 3D sound in three axes-left/right, front/back, and up/down. The best way to explain this is a dramatic expansion in the virtual soundstage. Instead of arbitrary left/right, you can suddenly hear subtle gradations in left-right sound positioning. It's as if someone took your speakers and moved them out about five feet in each respective direction. On top of this, there is a fairly strong front/rear axis that you can hear as well, even with only two speakers. It's sort of a muffling of the sound as it goes behind you, with Doppler effects as the sound zooms "past" you. I have to admit that I couldn't tell at all when sounds were supposed to be above me or below me. This is by no means a perfect effect, but it definitely succeeds in adding a new dimension to the sound.

Needless to say, I was floored! To think that all this time, I had gotten by with simple stereo, when there was clearly something so much better out there. It may not be true 3D sound in every sense of the word, but I assure you that it is worlds better than basic stereo by any measurement.

I've been a huge 3D sound proponent ever since. Aureal's version of 3D sound is called A3D, though other manufacturers have their own methods of generating the same types of effect with different names. The general industry acronym for this is HRTFs, or Head Related Transfer Functions. In layman's terms, these are filters that are applied to the sound to make them appear to originate from the correct direction and distance, even though in reality they're coming out of those two speakers right in front of you (or behind you, if you have quad mode enabled). There are two ways that games can support 3D sound: via the vendor's proprietary 3D API, or via Microsoft's DirectSound3D, which is part of DirectX. In either case, the results are similar since the HRTFs that are applied are exactly the same.