3D audio is a simulation of the natural positioning of sounds for various applications including video presentations and games, virtual environments and sound stages.
3D audio relies on a variety of technologies to create a more life-like or dramatic immersive experience for music, movies, video and video games as well as virtual reality (VR). The technologies are also used for training simulations, educational applications and even therapy.
Some 3D audio techniques use manually mixed tracks for voice, instruments, ambient sounds and sound effects that are spread among two or more speaker channels. Stereo, quadrophonic and numerous multi-speaker surround sound technologies are produced this way. Binaural 3D audio is produced by recording with dual microphones. This is an old technique often adopted by modern applications. Some binaural microphones simulate human hearing simply by placement of the microphones. Others based on biomimicry (the imitation of naturally-occurring systems) include anatomic models of the human ear or even the entire head. Binaural 3D audio is particularly well suited to virtual reality because it is easier to produce than other methods and also helps keep down the weight of VR headsets because it operates with only two speakers.
As is often the case, proprietary technologies and a lack of standardization are hindering development of the industry. Licensing of some technologies used for 3D audio can be quite expensive, and there are many competing formats. The pioneering Dolby Labs, for example, offers a large number of 3D audio formats based on various numbers of speakers. Other 3D audio companies include 3Dio, Auro, Dysonics, Ossic, RealSpace, Sennheiser and VisiSonics.
See and hear an introduction to 3D audio -- grab your headphones first: