when you turn on the noise cancel feature you can hear a very low rumble sound . I try these on a airplane and several other white noise environment , like fan blow . when compare these to regular headphone , there be no difference at all . a coworker let I try he bose noise cancel headset and that do make a noticeable difference . the noise cancel feature of these philip headphone appear to be worthless . the comfort and quality of these as just regular headphone be ok , but why would you buy these unless you want the noise cancel feature ?