I don't really know what could be happening here, and the people who answer me on the cakewalk forums are always really smart and nice so here we go. Any help or ideas for understanding what's going on here are greatly appreciated.
 
When I am wearing my mixing cans (which happen to be Sennheiser HD 380s, if that matters) and facing my computer directly, I hear a strange buzzy static noise. If I turn either 90 degrees to the left or about 60 degrees to the right, the buzzing stops. It decreases in volume as I turn towards the silent directions. Facing any other directions I will still hear the buzzing. It only happens when I plug the headphones in, and I'm not putting any undue stress on the cord.
 
I've had the headphones for about a year now and my computer about two years. The noise just started happening about a month ago. I can't think of anything significant that I've changed other than installing ProTools 11... ha. But in all seriousness, I haven't changed anything related to my hardware. I did buy a new mouse very recently, but the buzzing happened before that.
 
What could be causing this? Could it be a magnetic field issue? Something that changed outside of my building? Honestly I just don't even understand where to start, and googling is only getting me stuff about wiring problems in the headphones, which doesn't seem likely based on the change in the noise when facing different directions. But I know nothing, and that's why I'm posting. Thanks.

It sounds like your headphones may have a funky cable and you are sitting in close proximity to an electromagnetic field. If the shielding on the headphone cable breaks, they can act like antenna for EM fields. Try another set of cans and see what happens to the noise.

Thanks for your reply, John.  I tried several other pairs of headphones, none are buzzing. The cord doesn't look damaged at all from the outside, but I suppose something could have cracked on the inside. Replacement cords are pretty cheap so I'll try that.

*sigh*
 
Finally got the new cable in the mail, I'm hearing the buzzing on both of them. Should I just assume that the cable I got was similarly damaged?

Hi Candy, would you happen to have another pair of cans handy (nothing high-end necessary)?  It might be a matter of an old fashion process of elimination.  At least you know it may not be the cable.
 
Kind regards,
 
Living Room Rocker

Hi Living Room Locker,
 
Sorry for the delayed reply. As I replied to John, I have tried other pairs of headphones (three, all of different manufacturers, styles, and price range) and they are not having any problems. Do you have any ideas of what else might be causing the problem? Thanks!

Hi,
 
What kind of audio interface are you using?
Is the volume of the buzzing sound constant, or does it scale with the volume setting of your interface.
Are you using a laptop computer? If so, could you unplug the power supply?
Do you have a cell phone close to your computer?
Are you using a 3.5mm to 6.3mm adaptor?
 
What you are describing sounds like RF (radio frequency) interference or a parasitic oscillation. It could be that your headphones are picking up an electromagnetic field.
 
Wilko

I would agree. This sounds like RF interference. It is probably being introduced back into your mixer or audio interface by the headphone cable, causing subsequent noise to be re-amplified back to the phones. Cable shielding varies between devices which is possibly why other headphones don't show the problem.
The most common cause is a local TV transmitter tower or possibly a mobile phone mast, though this is less likely. I had dreadful problems in one house because of this. A quick solution may simply be to wrap the headphone cord around a ferrite toroid. You can get these from electronics suppliers. Make sure the hole in the middle is sufficiently large to accommodate the plug and then try wrapping the cable around the toroid a few times - initially, I'd try somewhere close to the plug end. You'll often see these sorts of toroids on power supply cables etc to stop RF radiation out of the power supply interfering with other devices.