What do people use to synchronize their christmas lights to music?
There are many options for this. Some are expensive, another is not.
LESS EXPENSIVE AND LOW TECH:
The GE Lights and Sounds of Christmas (found at Walmart, Lowes, Sears, …) sells for about $100. It gives you 6 individual circuits that control up to 1440 watts of preselected music and the lights are preprogrammed. It is essentially a plug and play.
There are three major manufacturers of hardware/software that allows you to program your lights via computer.
You pick a song, break it down into small segments of time (like 0.10 second segments) and tell each individual circuit of lights to turn on, off, fade, twinkle or shimmer.
D-Lights is the least expensive of the three, but you have to have the ability to assemble your own equipment.
LOR is the preferred vendor for residential displays. It is a complex software that takes you about 4 hours per minute of song for 32-48 channels to program. A channel is an individual circuit of lights that you choose to control.
Animated Lighting is the most expensive, yet it is easier to program. Their equipment is what is found on some residential displays and most commercial displays.
(Reprinted from Yahoo!)