tathra
bluelighter
its got "laurel" at low frequency playing at the same time it plays "yanny" at high frequency. both the speaker playing it and your hearing play a role in which one you hear, so try playing it through headphones and different equipment. like optical illusions, its possible to have it switch between both once you're able to isolate each one separately (every optical illusion does this for me); i think this is the first "audio illusion" anyone has come up with, or its at least the first one to become popular/viral.