What is pink noise?

Ok, this is fascinating. Since we've gotten the attention of folks who genuinely know their stuff, I've got one more that's been puzzling me -- "brown noise."

I'd never heard of this before geting thay Ayre burn-in disk, which has tracks of white, pink and brown noise (as well as some full frequency sweep tones). What am I getting with the brown noise besides an apparently deeper yet tone from the pink noise and a whole lot more exercise for the bass drivers?

is "brown noise" and fart the same thing?

If you ever heard one of her albums, you would know.

Alcides - your pink/white noise analysis is correct, but you're off by an octave on the piano's low end. The standard 88-key piano goes down to ~28Hz, also the 440Hz A is above middle C, not below.

So if you were going to measure in-room frequency response, would you use white noise or pink noise?
And how do you measure sound at any particular frequency? Rat Shack SPL meter and Stereophile test tones miss a large part of the frequency spectrum. I would think using white or pink noise would be much more accurate - IF it can be done.