Although I do science as my day job, I know astrophysics no better than you guys. That said, here are my $0.02 reading the news article:
(1) They are talking about a sound wave at frequencies in the order of 0.000000000000001 Hz (10^-15 Hz) -- if you still call it a "sound" wave. In other words, the cycle period of this sound is ~10 million years.
(2) The "medium" for this sound wave is apparently the plasma gas jetting out from a black hole.
(3) This far-subsonic sound wave has never actually reached the earth. Instead, they indirectly observed the existence of sound wave by observing a modulation of X-ray and other radiations shooting toward us from the plasma jets surrounding the black hole.
(4) I don't think any subwoofer lasts one cycle period of this sound.
