Noise canceling Headphones

For the past six months I have been looking for some kind of headphones to wear at work to protect my ears. I work in a noisy room and I think the constant background noise from the air conditioners and computer fans has damaged my hearing, causing a constant ringing in my ears. Headphones that just block out sound aren't made to be used 8 hours a day. I considered getting a pair of noise canceling headphones but I didn't know if they would work well enough, plus I couldn't find any I liked. Someone at Radio Shack suggested that I try the Bose store. So I went there this weekend and tried their premium headphones and boy did they work well. They can be used without any music and without being plugged into anything. This reduces the noise by taking the sound waves and inverting them, thus reducing the sound you hear. Using the headphones for music, like all Bose products, sounded great. I bought the set and tried them out on Monday. They did a great job of reducing the noise from the air conditioners, but not so good reducing the noise from loud people. There is a side effect though - they make me dizzy and nauseous! I can't explain that. Hopefully I'll get used to their effect and the dizziness will go away.