Noise Cancelling headphones turning up when activating noise cancel feature. Is that just a cheap gimmick?

Question

What I mean to say is, does it turn it up to make you think the noise around you got quieter?

Answer 1

no, quality headphones have a microphone that listens to outside noise and creates white noise to cancel out sound. thats why its called noise cancelling

Answer 2

It sounds like to got a set of cheap rip-offs to be honest.  What brand are they?  The real ones don't generate white noise.  As the other answer says, they have a mic that picks up outside sounds.  They then generate a sound of the exact same volume but in opposite phase that cancels the outside noise.  The only thing you should notice is that outside noises get very, very quite as they can't completely cancell all sound.  The noise cancelling effect also often only works on the low frequency sounds, not so much on the higher frequencies.  None of this should affect anything you're using the headphones to listen to.  You shouldn't notice any difference in the volume of the MP3 player you're listening to for example.