Worried about lag -- sound, collision, and timers

I’m working on a project that requires a sort of ticker, like in the action editor. Instead of the ticker moving, the background does though, so the ticker doesn’t move, while the background kind of slides past. There will be little ‘notes’ on the ‘background’ sliding past, and i want them to play when they line up with the arrow. My problem is, lag would be an issue. If the note causes the backgound to slow down, or the sound plays late, everything would be thrown off some.

Soooooooooo, what I want to know is how i should go about making the sound play. Should i have the ticker play a sound on collision with the ‘note’, via ray sensor, or via timer? I have worries about all of them. Keep in mind, the most important thing is that the sound plays when you see the ticker line up. If it slows down the game, thats bad, but not as bad as the sound playing 2 seconds after the ticker actual passes it.