Maybe your MacBook is fan of dubstep ;) I'd say the audio is leaking into the fan controller, and your dubstep just happens to contain the pattern that's sent

Maybe your MacBook is fan of dubstep ;) I'd say the audio is leaking into the fan controller, and your dubstep just happens to contain the pattern that's sent to the controller to signal spin up. the controller probably uses some simple serial bus protocol, maybe i2c. Edit: For people who are more adept at peeping at the song's spectrum: on the Apple forum people report the fan speedup to occur at 0:28, 1:47, 2:05/2:10, 2:30, and 3:50