Is this an illusion...or does it really get higher every time?

Question

http://www.boingboing.net/2008/07/28/amazing-auditory-ill.html

Answer 1

I thought that was kind of cool.

Answer 2

Yes an iluusion. Its the way its played. It you stop and the middle then start over you can tell its just an illusion.

Answer 3

It's an illusion.

It works by combining tones as it plays the scale, At the end of the scale, the tones are actually close to the beginning of it.

The rest of the explanation on that site I found a little confusing and even a little misleading, but if you think about it carefully, you'll get it.