Blueswan sounds about half-right. Pink noise has equal energy per octave. White noise has equal energy at all frequencies.
One virtue of pink noise is that it's an easy way to test frequency response. It's much easier to hear differences in frequency response when listening to pink noise than when listening to music. That's because, in music, there might be little or no energy in the frequency range where the difference occurs, or what energy exists is masked by louder sounds at other frequencies.
On the other hand, pink noise would be a lousy way to test transient response or imaging!
One virtue of pink noise is that it's an easy way to test frequency response. It's much easier to hear differences in frequency response when listening to pink noise than when listening to music. That's because, in music, there might be little or no energy in the frequency range where the difference occurs, or what energy exists is masked by louder sounds at other frequencies.
On the other hand, pink noise would be a lousy way to test transient response or imaging!