NASA astrophysicists have sped up the sound waves of the Perseus black hole so that humans can hear the spacey moans. From the New York Times:
In 2003 astrophysicists working with NASA's orbiting Chandra X-ray Observatory detected a pattern of ripples in the X-ray glow of a giant cluster of galaxies in the constellation Perseus. They were pressure waves — that is to say, sound waves — 30,000 light-years across and radiating outward through the thin, ultrahot gas that suffuses galaxy clusters. They were caused by periodic explosions from a supermassive black hole at the center of the cluster, which is 250 million light-years away and contains thousands of galaxies.
With a period of oscillation of 10 million years, the sound waves were acoustically equivalent to a B-flat 57 octaves below middle C, a tone that the black hole has apparently been holding for the last two billion years. Astronomers suspect that these waves act as a brake on star formation, keeping the gas in the cluster too hot to condense into new stars.
The Chandra astronomers recently "sonified" these ripples by speeding up the signals to 57 or 58 octaves above their original pitch, boosting their frequency quadrillions of times to make them audible to the human ear.