Surround sound is created in several ways. The first and simplest method is using a surround sound recording technique—capturing two distinct stereo images, one for the front and one for the back or by using a dedicated setup, e.g. an augmented Decca tree and/or mixing in surround sound for playback on an audio system using speakers encircling the listener to play audio from different directions. A second approach is processing the audio with psychoacoustic sound localisation methods to simulate a two-dimensional (2-D) sound field with headphones. A third approach, based on Huygens' principle, attempts reconstructing the recorded sound field wave fronts within the listening space; an "audio hologram" form. One form, wave field synthesis (WFS), produces a sound field with an even error field over the entire area. Commercial WFS systems, currently marketed by companies Sonic Emotion and Losono, require many loudspeakers and significant computing power.
Part of the problem for multichannel music is that no one ever really figured out what to do with the extra channels. Four-channel Quadraphonic surround recordings first appeared in the early 1970s, but 40 years on the engineers still haven't figured out what to do with all of those channels for music. The only person really who has consistently produced albums for 5.1 specifically is Steven Wilson.
Wilson has become known for his 5.1 surround sound mixes, with the 2007 Porcupine Tree album Fear of a Blank Planet nominated for a Grammy Award in the "Best Mix For Surround Sound" category. It was also voted #3 album of the year by Sound And Vision. Wilson has worked on several other surround sound projects, which have included remixing the Jethro Tull and King Crimson back catalogues, as well as Marillion's 1985 album Misplaced Childhood.The Anathema album We're Here Because We're Here was mixed by Wilson and he is thanked in the album liner notes, and he mixed two songs on their subsequent album Distant Satellites. He also did the remix for In the Land of Grey and Pink by Canterbury scene band Caravan. The first three new editions were issued in October 2009, with more emerging in batches over the coming years. Wilson is responsible for the 5.1 and new stereo mixes of the 1992 XTC album Nonsuch in 2013, as well as the Gentle Giant albums The Power and the Glory and Octopus in 2014 and 2015, respectively.
Perhaps one of the most common forms of 5.1 or Surround music is that of concerts or live performances, where elements such as the crowd and the stadium can be implemented into the surrounds and provide a much more immersive environment for the consumer. Now in saying this there is nothing stopping someone from utilising elements from this concept and even film mixing techniques where by, vocals can be placed into centre speaker and effects and reverbs can be placed into surrounds. Even then the art of surround sound mixing is subjective and is open to many different forms of interpretation which raises the age old question, Band perspective or Audience perspective. While this is up to the Engineer or Producer the same concepts for mixing in surround apply for things such as De-Correlation, Filtering (particularly for LFE channel), Compression, EQ etc; which can be done for each individual channel or linked to relative parings or positions (ie; Rear Surrounds, Stereo front, Centre, LFE)
The most common process used for mixing in any format is De-Correlation. This is referred to as a process whereby an audio source signal is transformed into multiple output signals with waveforms that appear different from one another, but of which have the same sound source. Put simply it is a by-product of acoustic or electronic processes that often change the sound of the source. Many studies have shown that Colouration and Combing can be eliminated when a delayed signal is de-correlated from the leading signal and then the delay is offset back to zero. the degree in which Colouration and Combing are removed depends on the amount of correlation between the two signals.
Of course there is nothing stopping you from using reverse methods to use creative spacial imaging similar to a blog where I talk about phase cancelation to create a perception of the depth of audio "LINK HERE".
With all of this in mind, apart from consumers listening to music wither predominately on mobile devices or through headphones; you may ask yourself 'Why Release In Surround?'
With the rise of many Virtual Surround Platforms such as Waves NX and VR, the possibilities are endless. Some applications could be as simple as Facebook360 and Augmented Reality, giving consumers a different experience to what would be just a Stereophonic or even Monophonic performance by altering the perception of the listener to give a much more immersive environment and a deeper connection with the media. Imagine standing on stage with your favourite star or band and experiencing the full depth of the performance as if you are part of it.
Kendall, Gary. (1996). The Decorrelation of Audio Signals and Its Impact on Spatial Imagery. Computer Music Journal. 19. 10.2307/3680992.