While viewing the interaction, the audio may start automatically or on click. By default, the audio starts automatically.

To change audio start settings, tick the Enable playback controls checkbox.  

After that, the Start field will go active and two options will be available: Automatically and On Click.

If you want users to manage the audio playback on their own, choose the On Click option. To get the audio started as soon as the user opens the slide, choose the Automatically option.