[Jack Degelia]

he’s correct. at the top of your timeline you will see a red line. that means your timeline sequence needs to be rendered. the beep, beep, beep you hear means that audio needs to be rendered. when that happens, just press the option + R keys and render your timeline sequence. make sure your RT settings, found in the lower left side of the timeline are set at Unlimited, Dynamic, Dynamic. that setting will aid in preventing frequent need to render.

hope this helps