mute sound

Hi

you can mute the volume

Using the Audio Tools
Articulate Storyline has some quick-access tools for previewing audio, adjusting volume, launching the built-in audio editor, switching to a different audio file, and exporting audio clips. Click the audio icon at the lower left corner of the slide or click the audio track in the timeline to reveal the Audio Tools—Options tab on the ribbon.

 Previewing Audio
Click Preview to hear the selected audio track. Click it again to stop the audio playback.

Tip: Another way to preview an audio track is to double-click the audio icon at the lower left corner of the slide. Single-click it to stop the audio playback.

Adjusting Volume
Click Audio Volume to change the relative volume of your audio track, then choose one of the following levels:

Low: Lowers the volume to 50% of the original.
Medium: Sets the volume at 100%, meaning there's no change to the original volume. This is the default option.
High: Raises the volume to 150% of the original.
Mute: Silences the selected audio track.