One interesting observation on surround sound is how its use has settled over the decades as musicians, producers and music listeners work out the capabilities, strengths and weaknesses of making music in surround sound.
When stereo was first invented, the pioneering record producers, such as George Martin with the Beatles, took full advantage of the new format and hard panned various instruments, drums and voices to create a novel and exciting listening experience.
With time, however, a convention has evolved where by now most modern recordings pan the key elements dead centre - bass, kick, vocals etc - then create a stereo image with the remaining instruments. This gives a more solid and powerful sound and makes music more compatible with less-than-ideal listening conditions. Anybody who has sat in a pub listening to a Beatles album, only able to hear half the band through the one speaker that’s nearby will know about that.
The same has happened to surround sound over time, though the convention is less strictly adhered to than a standard stereo image.
Early surround recordings experimented with putting the listener in the middle of the sound stage and panning different instruments all around. This can sound fantastic if you’re sitting in the correct place, are playing it loud and concentrating solely on the music, however if you just want some background music then instruments popping up all around your living room doesn’t always work.
Surround mixes have found some kind of equilibrium too, with vocals sent to the centre channel or in mono across all three front channels and the rear channels are now used more frequently for ambience and quieter sound than horn sections, guitars and backing vocals.
Classical recordings can make impressive use of surround sound by having the sound stage of the orchestra spread across the front channels and the surround channels recreating the ambience of the concert hall.