The popularity of the iPod has given new urgency to an old criticism of the portable music player: namely, that it isolates the listener by tuning out the world around him. As one response to this problem, Noah Vawter, a graduate student at the M.I.T. Media Lab, has created a pair of headphones that tunes the listener back in.
The device, which Vawter calls Ambient Addition, consists of two headphones with transparent earpieces, each equipped with a microphone and a speaker. The microphones sample the background noise in the immediate vicinity — wind blowing through the trees, traffic, a cellphone conversation. Then, with the help of a small digital signal-processing chip, the headphones make music from these sounds. For instance, percussive sounds like footsteps and coughs are sequenced into a stuttering pattern, and all the noises are tuned so that they fuse into a coherent, slowly changing set of harmonies.
The overall effect is a bit like listening to U2 with the vocals removed. Vawter is working on a version of the device that would rearrange the noises around the user to approximate any given pop song.