An application for a two-way communication system for communicating with a
person who is within a closed vehicle includes a short-range radio
transmission to transmit audio to a radio within the vehicle.
Communication from the person is done by reflecting a light beam on a
window of the vehicle and receiving the light beam, which is modulated by
vibration of the window caused by the person's voice. The received light
beam is then processed to reproduce the sound of the person's voice.