I looked over your site and couldn’t find a question along this line. I work in an office with the “Open” ceiling exposed lights kind of thing. The lights are like ones you would find in a warehouse. HDI lights with ballasts. At any rate, there is a CONSTANT buzzing sound that comes from the lights. A group of us spoke to HR and they said they would be happy to provide us with earplugs. Good earplugs that will actually block the sound are not conducive to working in the office and answering the phone. Lately three of the people I work with and I have almost constant headaches. At night when the lights are turned off (when we work after the rest of the people have gone home) the headache will disappear after 10 -15 minutes. Any ideas?