http://en.wikipedia.org/wiki/Shepard_tone
edit: …and now reading that I've stumbled across the Tritone paradox which I wasn't familiar with and is equally cool.
http://en.wikipedia.org/wiki/Tritone_paradox http://deutsch.ucsd.edu/psychology/pages.php?i=206
http://en.wikipedia.org/wiki/Shepard_tone
edit: …and now reading that I've stumbled across the Tritone paradox which I wasn't familiar with and is equally cool.
http://en.wikipedia.org/wiki/Tritone_paradox http://deutsch.ucsd.edu/psychology/pages.php?i=206