Originally Posted by obobskivich
I thought basic A3D support was kind of a de facto standard, just like basic EAX. At least for modern-ish hardware (Aureal hardware was still sold as Turtle Beach until a year or so ago, I believe VIA and C-Media hardware still supports A3D) - I could be entirely wrong though, I can't actually think of a single game that needs A3D over EAX or something else. A3D is like GLiDE, it's neat to read about but ultimately worthless in modern times.
A3D 1.0 is as prevalent as DirectSound3D. A3D 2.0 and 3.0, on the other hand...not so much. It doesn't help that only cards with the Vortex2 chipset can properly accelerate those.
In particular, A3D 2.0 added a wavetracing feature. It literally calculated how sounds reflected in the game environment, as opposed to having general environmental presets ala EAX. However, this did take a heavy toll on the CPUs of the time, which were already taxed enough with other aspects of the game engine. Aureal planned to release a DSP daughterboard for their SQ2500 card to alleviate that issue and call the combo the SQ3500 Turbo, but then they got bankrupted by their legal battles with Creative, and the rest is history.
While I can't think of any games where A3D sounds distinctly better than EAX, some die-hard Half-Life/Counter-Strike fans insist on A3D. Some claim that it allows people to hear sounds that are farther away compared to plain DirectSound3D or EAX. However, other statements raving about A3D in those games talk about how people with headphones could pinpoint sound sources while blindfolded...I get the impression that Aureal's main draw there wasn't the wavetracing, but that they were the first to implement binaural surround for headphones (and to a lesser extent, stereo speakers) long before anyone else thought of it for gaming. I'm even sure that CMSS-3D Headphone draws as much from Aureal tech as it does Sensaura tech.
To further add to the confusion, Aureal used A3D as a sort of brand...in addition to the API and DirectSound3D extensions, A3D 3.0 in particular also referred to middleware not much unlike the Miles Sound System or FMOD.