Check out this low cost project. This video will show you how to transfer sound over light! Yes, this is possible. You'll transfer a sound with a distance of 5 meters, but you may experiment on greater distances if you'd like. You'll need a laser (or an LED) for this audio project, one Opto transistor (or resistor), one 3-volt battery, two mono audio jacks, and some alligator clips. Just watch this cool electronic audio experiment and try it out yourself.