From Altec Lansing's Upgrader series ... Active Noise Cancellation Technology cancels out ambient external noise to enhance the clarity of your sound.
Scan are well known and there is free deliviery if you are an active member of Avforums (and other places). Not as cheap as the play offer (which was £17.99) but these are currently in stock.
A review rated them OK when priced at £90: (http://www.avreview.co.uk/news/article/mps/uan/2068)
We're big fans of Altec Lansing's speaker systems but were a little disappointed with their UHP805 headphones. The noise-cancelling aspect does work well. A small switch on the right-hand earpiece allows you to turn the noise-cancelling feature on or off, and you can certainly hear the background noise fade away as you do this. However, the sound quality seems a little muffled at times - as though the earpieces were padded with cotton wool. It's mainly the bass end of the scale that comes through at lower volumes, and you need to turn the volume up quite high before the mid- and upper frequencies start to punch through properly. To be fair though, the UHP805 is one of the less expensive sets of noise-cancelling headphones currently available, so they're worth considering if you're on a tight budget. The carrying case and airline adaptor also add to their value for money, especially if you travel a lot.
From the posts about these on the Play.com thread, it seems that opinion is heavily weighted against these headphones. See
After reading all the the threads here, exec summary is.....
* Not £79 headphones, more like £40 tops..
* The sound quality is poor, even worse when noise cancelling is off, hissing is really bad
* Any reviews on the net are poor, cable is too short
* They hurt your head