I noticed that when I hook a patch cable (TS 3.5mm phone jack) into the front input of my computer, and I touch the tip with my finger, and of course if I have some program setup for live playback, I get a tone, an audible tone. It's fundamental is 60 Hz and contains seemingly exclusively odd harmonics. I notice that if with my other hand I grab my metal bed frame (I have a loft with a table underneath, so as I sit at my computer, I just need to reach up to grab my bed frame), it gets louder. On the other hand if I touch both the tip and the sleeve of the phone jack, or if I put my other hand on my computer case, it quiets down. But if the cable is plugged into back panel input, this doesn't happen. So what exactly is happening? Some technical details to consider: 1) The front input is part of the computer case, so there's a cable running from it to a hook up on the motherboard, sharing space with a number of power cables for fans, disk drives, and the motherboard itself. Is this the noise source, or is it the human body's RF receptive properties? 2) The place where the front input cable meets the motherboard is right next to my wifi card, but the antenna's on the outside so I suspect that this is irrelevant. 3) I think I might have damaged the front input by not plugging a plug in all the way once.