Via Geek Press, we have some interesting audio illusions over at The New Scientist. I found this one particularly so:
Some pieces of music consist of high-speed arpeggios or other repeating patterns, which change only subtly. If they’re played fast enough, the brain picks up on the occasional notes that change, and links them together to form a melody. The melody disappears if the piece is played slowly.
This is called an emergent property, and while many emergent properties arise from a critical mass (say, of the number of ants in a colony), they can also do so as a result of speed. Some AI researchers argue that human intelligence (and non-human as well) is in fact a result of simply having enough neurons (and at a higher level) various cognitive functions in one place to a degree that consciousness emerges. Others (such as Searle) scoff at the notion, arguing that gathering a large number of entities together isn’t going to change their properties in a qualitative way, and that’s simply common sense. You can’t combine a lot of dumb things and somehow get something smart. The whole may be greater than the sum of its parts, but not (so to speak) the sum of its (not so) smarts.
The argument against this is to point out another non-intuitive result. Prior to Maxwell, who would have imagined that you could wave a magnet back and forth and create color? Well, if you just wave it slowly, you won’t–all you’ll see is someone waving a magnet. But wiggle it half a quadrillion times per second, and suddenly there’s a electromagnetic wave that, when captured by the eye, causes one to (literally) see red. The auditory phenomenon described above is similar–play it too slowly and the music disappears, but speed it up, and a melody emerges.