I’ve just found this fantastic auditory illusion after browsing through Tom’s blog. It’s a YouTube video but the visuals are just text, all you need to do is listen and replay.
It’s like the audio equivalent of a moving spiral. It always seems to be moving up but you realise after a while it can’t possibly be going anywhere. It’s remarkably compelling though.
I’m afraid I don’t know much about how it works, but I suspect it’s a form of Shepard tone.
The Shepard tone link above is a Wikipedia page, and if you scroll down through the page there’s a nice example of a continuous tone which seems to have the same effect.
The article also mentions that the effect has been used in the Muse song ‘Ruled by Secrecy’.