3D audio

3D audio effects are a group of sound effects that manipulate the sound produced by stereo speakers, surround-sound speakers, speaker-arrays, or headphones. This frequently involves the virtual placement of sound sources anywhere in three-dimensional space, including behind, above or below the listener.

3-D audio (processing) is the spatial domain convolution of sound waves using Head-related transfer functions. It is the phenomenon of transforming sound waves (using Head-related transfer function or HRTF filters and cross talk cancellation techniques) to mimic natural sounds waves, which emanate from a point in a 3-D space. It allows trickery of the brain using the ears and auditory nerves, pretending to place different sounds in different 3-D locations upon hearing the sounds, even though the sounds may just be produced from just 2 speakers (dissimilar to surround sound). [Note that, transfer function is a function that depict the relationship between an input and the output of a system. It’s a fraction representation with the denominator not equal to 1, if there’s feedback in the system. If the transfer function e.g. Z-transform is localized to the unit circle (or bi-unit circle or tri-unit circle for 2-D and 3-D cases respectively), it then becomes the Multidimensional Fourier Transform (see Multidimensional transform) or the frequency response of the system.]

Using head-related transfer functions and reverberation, the changes of sound on its way from the source (including reflections from walls and floors) to the listener's ear can be simulated. These effects include localization of sound sources behind, above and below the listener.

Some 3D technologies also convert binaural recordings to stereo recordings. MorrowSoundTrue3D converts binaural, stereo, 5.1 and other formats to 8.1 single and multiple zone 3D sound experiences in realtime.

3D Positional Audio effects emerged in the 1990s in PC and Game Consoles.

3D audio techniques have also been incorporated in music and video-game style music video arts. The Audioscape research project, provides musicians with a real-time 3D audiovisual content authoring and rendering environment, suitable for live performance applications.

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