My brother recently got a pair, the creative HN-700. He bought them to block out the radio at his work (yes, they have a radio on 24/7 in the office ) but they arn't very effective at this.
They will remove engine noise/low rumbles effectively, but are less effective with higher sounds. You can still hear people speak and as such will still be able to hear the TV. So yeah, good for the plane engine noise, but not very effective with voices/music
Noise cancling headphones are always going to negativly affect the sound they're producing. If you want to quiet the surrounding environment, just get yourself 'earmuff' style headphones, or use real earmuff's over a pair of earbuds.
Really though, why don't you just get earmuff style headphones? They make relativly unabtrusive ones, and they're usually found on higher 'monitor' quality headsets that are relativly inexpensive.
They will remove engine noise/low rumbles effectively, but are less effective with higher sounds. You can still hear people speak and as such will still be able to hear the TV. So yeah, good for the plane engine noise, but not very effective with voices/music
But that can be very useful in a factory or digging the road. I imagine those headphones were designed specifically for that purpose, to allow you to have a conversation with someone whilst using some deefeningly loud machinery.
They're virtually useless in industrial situations. They can't cancle out the power produced by something like heavy machinery at close distance. They might be able to cancle out a decent amount of mid range hum but that's about it. If you want privacy and fidelity do it the smart way, buy headphones that actually cover your ears! If you still want to be able to hear people around you then you probably shouldn't be listening to headphones in the first place. It's nigh impossible even with modern technology to only issolate the human voice out of a sound stream. Noise is after all a subjective thing. The primary frequencies of the human voice are also the frequencies we're both most sensative to and regardless of the frequency the loudest signal always wins.