How to create audio output and sync with arduino code

Other Hardware Audio
1

I'm trying to make a Christmas lights display.
Say I already have the code for the lights. All I need to do now is have music sync to it.

-How exactly do I allow my arduino to create audio output and sync it with my code?
-Could I use a wave shield? If so, how would I sync it?
-If I want to use my computer and speakers to play music, is there any way the arduino could communicate with my computer in order for it to play/sync music?

Thanks!

2

You could use a chip like this

to break the music into bands, then reading the outputs will allow you to sync with the music.

3

What about using FFT to detect music frequencies?