That seems a broad enough thread title to allow LOTs of drift I propose as a house rule for my thread that anything goes as long as it is "Quite Interesting" and somewhere near topic. To kick off the idea that what we hear - actually hear - not imagine - is fundamentally down to the signal processor we call the brain, I plan to start with STEREO - but I expect to end up all over the shop.
In effect we are saying the finished "sound" is not down to just the ears, any more than a recording is just down to the signal out of the microphone. A lot of processing goes on, and affects what we actually "hear". This means some things we hear, and some changes in what we hear are real - but they are changes in our hearing, and not necessarily changes in the equipment we are listening to.
STEREO. When I set up a new vinyl component, I stick on HFS69 and listen to that girl telling me that the following signal is recorded on both channels equally and in phase and should form a strongly defined central image. It does. The saxophone I hear Karen Sharp playing comes from a place just to the right of the Wii but a bit higher up, and Katie Melua on "Nobody knows you when you're down and out" comes from just left of the sky box. That's with my eyes open. I feel I could do better than point, I could get up and touch the place where the sound comes from, and expect to feel the speaker cone vibrate.
But of course - although I absolutely hear the sound come from that point - it doesnt. There are no sound waves at all being produced from the point where I absolutely hear them coming from. It's a con. They actually come, as the lady on the record says, from the right and left of there, equally and in phase. I am (I think) very lucky. The con of stereo works easily for me - and I love it. Others I know (we had some at PT, Clive197 appears to be one) don't get the illusion, and so don't get the imaging and positioning I do. A bit like I can't get 3d TV (I can't get 3d vision in reality having lost the sight of my right eye). And Gordon didn't get the oscillating ladies I posted a month or two back - rather missing the point that you weren't supposed to see through the illusion, you were supposed to trick your brain into seeing it, or not, at your choice.
But the point is, the most basic idea of the 2 channel most of us listen to now as our primary music source, is a con based on the discovery that you can fake a central image with real sound coming from 2 points in front of the listener. So we hear that central image - because that's how our brain hears, even though we don't hear it, because it's actually not there.
Our brains can get influenced by many other things - which is why the fact that we hear changes doesn't necessarily mean a change has taken place, any more than the fact that I hear a sound coming from the centre of my TV means it actually is coming from there.
Amazing brain
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