Mono, Stereo, Surround?

Some people swear by mono recordings, claiming they sound more "pure" than any other format. One case in point is the early Beatles recordings in mono. They sounded a little rough but the music came through. Then some of the recordings were re-released in two-track stereo and did not sound as good. It was disconcerting to hear John on one channel, George and Paul on the other, and nothing in between. This was an artificial recording artifact created in the studio. So a lot of people preferred the mono versions.

Monophonic devices (aside from your clock radio) are actually becoming more common: Bluetooth speakers, gadgets like the Amazon Dot, Google Nest, etc. These are fine for information purposes (news, weather, device control around the house) and casual background music. The problem is this: mono recordings convey no spatial location cues or ambiance information whatsoever. We have two ears, so we are binaural listeners. We interpret the location of individual sounds and frequencies based on the time delay and phase relationships of the air pressures reaching our ears at slightly different times. So if your goal is to create the illusion of a live performance, mono is a non-starter.

On the other extreme, surround sound (5.1 or 7.1 channel, recently Dolby Atmos) is typically used to create a more "immersive" sound environment. This works for movies with special sound effects and provides the illusion of sounds to the side and behind you (and with Atmos, above you). I recall when quadrophonic recordings were released for the audiophile community (this was many years ago). This required a 4-track reel-to-reel tape deck and specially recorded music. Speakers were placed at the 4 corners of the listening space. The general response was "meh".

Surround (or even the old quad stuff) sound would be nifty if you wanted to experience what it would be like to be one of the musicians sitting in the middle of an orchestra. If a recording correctly placed all the other instruments in the space around you, then that is what you would hear when it is played back. But who wants that? What you want to hear is a simulation of what you would experience sitting in the audience. And for that, stereo is the best we have. In fact, some of the best recordings are "binaural" - recorded with a simple single pair of microphones spaced the same distance apart as human ears and positioned in a venue where the sweet spot for listening would be.

I am not in any way knocking surround sound for a home theater setup. What I am talking about is music reproduction, pure and simple. But here is one problem I have with surround sound with video: if you looking at a flat, 2-dimensional movie screen or TV, the visual experience is not immersive, but the sound is, so we have to force ourselves to artificially believe we are "in the scene". This is tricky for our brains to do. Attempts at 3-D (to make the visual experience more immersive) have generally fizzled. The other situation where immersive sound WOULD make a lot of sense would be VR (Virtual Reality). In this case, the visual experience IS immersive, so the sound should match and be perfectly synchronized to what we see as we interact with the simulated environment. I don't think the technology is quite there yet, but I will not be surprised if we see it soon. Or maybe it will come with practical holographic projection.

Being surrounded by sounds or sound effects is not what you hear when listening to a live music performance. What you hear is the sound coming directly from the performers (and often a sound reinforcement system) and a reverberant field. This reverberant field is a function of the venue and can be either pleasing or annoying if there is too much echo.

So IMHO, stereo reproduction is best for recreating the illusion of a live performance. If you want to gimmick the experience, then there are lots of tricks you can apply to the recording, but you are polluting the sound.

If you want to read more and get into some of the technical details, read this article at Linkwitz Labs titled "The Magic in 2-Channel Sound Reproduction".