Final Year Electronics Project Idea: Noise Cancelling Earphones

This concept has been developed, by Bose Audio (not sure though), but I think there's still lot of scope for improvement.

The idea is to develop earphone that will cancel the background noise and output pure music through the speakers. This can be achieved by setting up microphones along with the speakers that detect the noise from surroundings and cancels it so that the listener only gets pure audio through the speakers.

What do you think? Workable?