This is a really interesting Arduino project that involves manipulating stereo sound so it appears to move in a virtual 3-dimensional space. There is a lot of interesting information in the forum and the code can be found here.

The effect is so sharp, you can tell the difference between center, ten degrees left of center and ten degrees right of center. I was so surprised, I thought it might be due to wishful thinking, so I turned off the stereo volume adjustments… even with just the delay and no change in the volume between left and right, you can hear the sound move from side to side. What’s even weirder is that if you listen to just one side, the sound stays the same.

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