What's the best way to create accurate audio timing system (bars,beats) ?

Hey. I’m working on a project in which audio samples must be synchronized. The player turns them on and off, but does not have to worry about “getting to the beat”.

Don’t know about BEST WAY. If you’re in blueprints, check out timelines:

and timers:
https://docs.unrealengine.com/latest/INT/Gameplay/HowTo/UseTimers/Blueprints/index.html