3D Audio and Acoustic Environment Modeling
Published on Dec 17, 2015
Recently there has been a proliferation of 3D audio technologies intended for desktop computers. Many sound cards, multimedia speakers, video games, audio software, and CD-ROMs are marketed as having some sort of 3D capability.
In addition, a new technology called acoustic environment modeling has emerged which combines basic 3D technology with reverberation and other effects in order to simulate natural acoustic scenes. This paper describes the 3D audio and acoustic environment modeling technology developed by Wave Arts, Inc.
Wave Arts technology is the result of extensive research and development by Bill Gardner, a graduate of the MIT Media Lab. Dr. Gardner's research at the Media Lab focused on the key technologies of 3D audio: binaural synthesis [8,11,13], crosstalk cancellation [9,11-13], and reverberation algorithms [4,5,7,10]. The Wave Arts 3D technology has recently been incorporated into the In Motion 3D Audio Producer software, developed jointly with Human Machine Interfaces, Inc.
A 3D audio system has the ability to position sounds all around a listener. The sounds are actually created by the loudspeakers (or headphones), but the listener's perception is that the sounds come from arbitrary points in space. This is similar to stereo panning in conventional stereo systems: sounds can be panned to locations between the two loudspeakers, creating virtual or "phantom" images of the sound where there is no loudspeaker. However, conventional stereo systems generally cannot position sounds to the sides or rear of the listener, nor above or below the listener. A 3D audio system attempts to do just that.
A lot of commercial audio products are described as having 3D capability, but in fact there is great disparity between the various technologies in use. Unfortunately, many of the weakest products are marketed with the most exaggerated claims. For example, a number of stereo multimedia speakers are marketed as having "3D" technology. These speakers incorporate a simple circuit that has the effect of widening the perceived sound field of a stereo recording.
That is, the sound images that would normally extend to the locations of the left and right speakers are widened to extend beyond the speakers. These systems should more properly be called stereo enhancement or "widening" systems. They have no ability to neither position individual sounds around a listener, nor do they have the ability to position sounds behind, above, or below the listener. We use the term 3D audio to describe a much more sophisticated system than can ideally position sounds anywhere around a listener.
Even within the field of what we would consider to be true 3D technology, there is a wide range of technologies in use, with corresponding variation in the performance and cost of the products.
Compounding this is the fact that even the best technologies are subject to unavoidable limitations that guarantee that the performance of 3D audio will always fall a bit short of the marketing claims. This has created some confusion in the marketplace. Nevertheless, 3D technology is rapidly improving, thanks in part to the increasing availability of inexpensive computational power.
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