" Black holes generate sound. There’s one in the Perseus cluster of galaxies, 250 million light-years away. The signal was detected in 2003 in the form of X-rays (which will happily travel anywhere) by NASA’s Chandra X-ray Observatory satellite. No one will ever hear it, though. It’s 57 octaves lower than middle C: over a million billion times deeper than the limits of human hearing. It’s the deepest note ever detected from any object anywhere in the universe and it makes a noise in the pitch of B flat—the same as a vuvuzela. "

― John Lloyd , The Second Book of General Ignorance: Everything You Think You Know Is (Still) Wrong