Audio and button to advance

It sounds like you want to ensure the audio completes before the user can advance to the next slide, and you want the user to click the Next button (or similar button) to advance. 

• If you want all of the slides to prevent the user from advancing until the timeline completes, set the Player navigation to Restricted.
• If only some slides need to be restricted, use triggers to control when the Next button is disabled and enabled based on a variable value and/or other condition(s).

This post has details about those different ways to control the Next button: TIP: Controlling the NEXT Button 101 - Articulate Storyline Discussions - E-Learning Heroes