The L and R labels on your headphones serve a purpose, and it isn't just about fit. The audio source - whether it's a receiver, PC or MP3 player - sends left- and right-channel sounds to the appropriate earbud. While it might seem minor, this can be a difference between a disjointed experience listening to music, movies and other video, to a fuller experience that connects sight (in the case of video) and sound - with sound coming from the direction it's intended. There's no chance of a mix-up with the Universal Earphones being developed by Igarashi Design Interfaces Project in Tokyo - the headphones decide for themselves which ear they are in, and send sound to the each channel accordingly.
The Universal Earphones contain a microchip in the earbud that senses whether it is exposed to open air in the front of the ear, or in proximity to the back of the ear. Once the earphones determine which ear is left and right, it directs the left channel sound to the left ear, and right channel sound to the right.
The benefit of a Universal Earphone is that users don't have to stop what they're doing and look for the L and the R markings to insert the earbuds in the appropriate ears. A second benefit is that when a user shares the earphones with a friend, the Universal Earphones detect the situation and send a combined left and right signal to each earbud. This means all of the sound is transmitted equally rather than directionally. In this case the earphones detect that they are being shared by sending a low electrical current from one earbud to the other. If a single user is wearing the earphones, the connection is unbroken. When two users are sharing the earphones, the electrical current is broken and the Universal Earphones treat it as a shared mode with full sound to each side.
Additional features are in development such as a sensor that can determine when the earphones are not in the ears, which might have a command such as to pause the music or audio source and resume when earbuds are placed back in ears.
Igarashi Design Interfaces Project says the Universal Earphone design will be cheap to implement and is presenting the concept at the 2012 International Conference on Intelligent User Interfaces in Lisbon, Portugal, later this month.
Source: Igarashi Design Interfaces Project via New Scientist
Universal Earphones: Earphones with Automatic Side and Shared Use Detection from Kohei Matsumura