3D sound
3D sound is sound that feels like it has been generated in a spatially realistic manner.
It is optionally updating according to the user's head position and environment, such as by using 6DOF tracking. 6DOF is most useful for soundfield.
3D sound has been done often times when the reverberance of a physical space in which a sound is recorded matches that of the listener's environment. This often happens by accident if using standard stereo sound rendering.
Binaural audio[edit]
Mono recordings only use one microphone and both of your speakers would be playing out the same soundtrack. Stereo recordings on the other hand use two separate microphones at a distance from each other, one meant for your left speaker or earphone to play, while the other records audio for your right ear.
Binaural audio is audio that has two channels.
The method for recording and reproducing 3D audio, also known as binaural audio, goes back to the late 19th century.[1] The simplest form of binaural recording requires two microphones placed roughly in the same distance as is the average position of human ears. In a more complex method, both of the microphones are placed inside ear-shaped bodies at an optimum distance from one another as well as the source of the audio. This method allows the recording to mimic real life sounds. There are, of course, many additional factors that have to be considered in order to produce a high-quality recording. One of these include the shape of the outer and inner ear, the so-called head shadow, or a proper frequency response compensation in the playback device.
The playback gadget is of special significance since binaural audio requires headphones or a distinct stereo setup to work properly. Regular speakers exhibit various degrees of so-called crosstalk, which means that sound from speaker A mixes with sound from speaker B and cancels the binaural effect out. Speakers need to be placed closely together at 10-30 degrees for crosstalk to be minimized. Headphones do not have this problem and the only real requirement is a proper sound isolation. An open design shows slightly better acoustic properties for binaural audio, but this is actually quite negligible when we consider just how big differences in anatomy can be found, for example, just between males and females. A single pair of headphones simply cannot fit perfectly on everybody. The good news is that this is not really a problem because the effect is very convincing even with just an average pair of earbuds or headphones.
3D audio and virtual reality[edit]
3D audio can be used to create realistic and immersive virtual reality experiences.
At CES 2015, Oculus VR licensed a 3D Audio engine called RealSpace 3D. The 3D audio solution relies on a pair of adjustable on-ear headphones that are connected to the rest of the HMD. Those who were lucky to try it out said that it helped significantly increase the overall immersion. Chief Scientist at Oculus, Michael Abrash, said that 3D sound is not an addition to VR but a multiplier. Unlike regular video games, virtual reality is able to use 3D audio cues to help players orient themselves in the environment and experience a complete immersion. 2D displays have a limited field of view and lack the necessary information about distance, which means that while we may know from which direction is a certain sound coming, we would probably not be able to precisely estimate how far from us is its source.