The latest installment of AsapSCIENCE opens with a demonstration of the McGurk Effect, a powerful auditory illusion that demonstrates how what we see influences what we hear. But even more baffling is the Shepard tone illusion – a sort of sonic barber's pole that seems to continually ascend in pitch, without actually doing so.
The video also includes a great demonstration of the "tritone paradox," created by auditory illusion researcher Diana Deutsch (see her page for many fascinating illusions of music and speech). It's a fun one to try the next time you're hanging out with a group of people. That being said, the Shepard tone illusion remains the most impressive bit of aural trickery in our book. Here's an in-depth explanation of the illusion from professor David Huron of the Ohio State University School of Music: