How can I make media stop when user clicks on a button?

I have a slide that has narration that begins when the slide appears.  On the slide are several buttons that bring up layers with additional information.  Each of these layers has an  ear icon that when clicked, allows the user to hear the text on the slide layer.

Is there a way to cause an automatic exit from the narration on the main slide when the user clicks either the button that brings up the new layer, or the ear icon on the layer, to prevent both media files from playing at once?

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