Weird low hum under all music?

[LenkoCambria]

Hi all, just reporting a strange, low frequency humming sound I can hear behind all music in-game. I haven't played in a few months, but since applying the new patch, this hum is audible. It's not my speakers, and isn't constantly present - just during in-game music.

[Zade]

are your speakers plugged into the ports on the front of the PC or the back? sometimes you will pick up hard drive sounds through the front bus