The sound of a black hole?

Well, sort of. Sound is the movement of pressure waves through a medium that ultimately cause an auditory impression in a listener. A black hole in the Perseus cluster generates pressure waves in the cloud of hot gasses surrounding it. The frequency of these pressure waves is far below the range of what humans perceive as sound. But, when they are shifted quadrillions of times higher in frequency, this is what results.

It’s weird. It’s cool. If I ever write a horror story for Generation Mars, this will be playing in the background. But to call it the “sound” of a black hole is a stretch.