Wasn't it something like the reverse w/ Aphex Twin? Thought he made a song that projected as certain pics when put through spectrum analyzer. Yeah, that's really sweet- sounds pretty gnarly, too. EDIT come to think of it, you're right, he must've started out with the image and worked toward the sound a la this tutorial. Would be way too difficult the other way around...
Images and audio are more or less the same from a signal processing perspective. A spectrum analyzer is applying a Fourier transform to the audio signal. Apply an inverse Fourier transform to an image and interpret it as audio and you have audio that produces an image in the spectrum analyzer.
Made the mistake of trying to look up "Fourier transform." This is why I was a liberal arts major. Ouch. bfv, do you have a background in audio engineering? Or is this just kind of a "no duh" for anybody w/ physics/engineering/computer background?
It would be an obvious thing to anyone who studied signal processing. I haven't done much with audio.
The Gimp has FFT/inverse FFT filters, I have no idea whether following these instructions will result in Audacity actually interpreting the image as the equivalent audio signal though.