For some years now there have been available active anti-noise headphones, Sennheiser being one of the best known makers, unfortunately they would be a very expensive investment for a non music lover like me. These work by producing a mirror of the ambient noises' waveform, shifting it by a half-phase and injecting it into the speakers in a headphone, this having the effect of significantly attenuating the noise heard by the wearer. It would seem to me that all the processing and sound handling capability needed to do this is available on a PC or even a lap-top, so a microphone attached to a headphone to sample the ambient noise and hey presto! near silence on the train, plane, at a truckstop or in my own ******* living room when (post-deaf IMO) Mrs Wakou insists on scanning the TV to find the noisiest channel available (war film, western etc) and having the volume at industrial injury level ("so I can follow it from the kitchen"). Could anyone here please point me to where this might be discussed, and where someone could advise me as to whether this is possible? Alternatively, the circuitry for such a device would surely not be all that complicated, anyone like to have a stab at one, or know where a circuit diagram could be found?