I've been looking for a set of headphones to use in an open-office environment for a long time. I've tried several active noise-cancelling headphones, and several passive ones too. But haven't found any that were both effective and comfortable enough to use for a full workday. When I tried these ones, I was totally amazed. All the noise in the office was dimmed to barely perceptible level, even conversations more or less next to my desk. More telling though, was the fact that I used to have my Creative Zen Vision MP3 player at volume 20 (out of 25) to be able to overpower the office noise. After I started using these headphones though, I could put the music down to volume 10 on the player. I could even put it down further and still overpower the office noise, but then the music would be too low. They're also quite comfortable headphones, though they do tend to get a little hot on warm days. No problems at normal temperatures though. If you're looking for a set of headphones to protect your ears and concentration in a noisy office, look no further!