What is pink noise?

Pink noise, also known as 1/f noise, is a sound that has equal energy in all octaves. It primarily consists of low frequency sounds. Due to practical constraints, pink noise can be produced only over a certain range of frequencies and occurs naturally. Astronauts listening to electromagnetic radiation in outer space have noted it being emitted from certain stars. In biology, it is produced by the heartbeat and has shown up in DNA sequence statistics.