A3D Sound

Originally developed in 1997 in collaboration NASA (National Aeronautics and Space Administration) for use in flight simulators, Aureal's A3D technology has subsequently progressed through a number of versions.

ASD1 improved upon DS3D by providing hardware acceleration, a more advanced distance model allowing simulation of different atmospheric environments, such as thick fog or underwater and a resource manager that allows developers to take advantage of the number of 3D streams the sound card can handle and control use of Aureal's 3D sound algorithms.

The A3D2 version actually takes the geometry information of the room that is fed to the graphics card, and uses it to render realistic sonic reflections and occlusions . Using a technology called WaveTracing, A3D2 genuinely calculates up to 60 first-order reflections, which interact in real time with the environment, and then groups later-order reflections into overall reverb.

ASD3 takes the technology to the next level by adding a number of new features:

Volumetric Sound Sources: When developers define an audio file to a sound source, the sound source must have a location so that it can be rendered in relation to the listener. This is usually done via a point source: the point where the source is. However, some sources will not "reside" in a single point; flowing water, wind, crowd cheers, etc. will actually stretch out or extend in various areas. To more accurately model these sources, ASD3 allows them to be defined as volumetric sound sources, thereby positioning them better.
MP3 playback: Previously, audio streams for 3D audio have had to be WAV files. Now, MP3 files can be used, thereby both reducing their associated storage space and increasing their quality.
Reverb: The sum of all late order reflections. Aureal's geometric reverb will work on Vortex2 (and later) cards, as well as automatically translating to EAX or I3DL2 if a sound card does not have the appropriate A3D support.
Streaming Audio: Automatic support for streaming audio has been added, eliminating the complex layer of development normally required for client/server interactive entertainment applications that use existing audio solutions.

A3D2 was such a computationally complex system that Aureal developed a processor dedicated to the necessary number crunching. A3D3 requires even greater processing power, which is provided in the shape of an additional DSP to accelerate the new commands.

The fact that AD3 was considered by many to be the technically superior standard proved of little consequence when, after two years of litigation with Creative Technologies, Aureal filed for bankruptcy in April 2000 and was subsequently taken over by its erstwhile rival a few months later.