Sound to light

This is a simple sound to light circuit I soldered together. The system glows red when the inbuilt mic picks up sound. It can be adjusted to respond to different sound levels. The ideal would be to create a system which is not dependent on batteries, but translates sound energy into light. I'm not sure if the technology is there yet but I am looking into it. If I did manage to build a system I would place it next to the M25 at Gunpowder Park. Perhaps the miniature lights could be configured to form a text which became activated during heavy traffic usage, and capable of communicating with drivers.