We're used to illusions being optical. These visual tricks are designed by magicians and masters of the craft to leave us questioning our own eyes. But it's quite another thing to be left questioning our ears.
Give the video below a listen, and then let it replay (it should do so automatically). The same notes are being played each time -- it's just the same clip, over and over -- but it's weird how they seem to keep going up in pitch.
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