I've found that working with electronic equipment often means that you'll be subject to various levels of noise. Computers have fans on their motherboards, processors and graphic cards. Monitors often also make a high pitch sound when their power is on but not in use. I've found that working with a laptop is actually easier to handle.
I found another source of noise today which had been affecting me without my awareness. I find that high pitch sounds are quite insidious, you don't notice them but their affect accumulates over time. The source of my noise today was my halogen lights. Often halogen lights make a buzzing sound but for some reason mine were making a high pitch sounds. Not sure what I can do about the situation other than having the main lights off. Help, I'm down to mood lighting!