Help with Play/Pause media

Hello...

I'm doing a project about water and, as kind of a glossary, I have text highlighted in text box and when the mouse hovers over a caption comes appears (normal state, before was hidden) with the explanation of the text.

I want it to pause the narration while the caption in in normal state and continue the narration when it goes back to hidden state.

I was able to do that with the pause/play media but I have a slide with several layers and when I move to the other layers I have simultaneous sounds playing if the user doesn't stay in determinate layer until the narration finishes.

I don't know if I'm making myself clear...

Please find the file in attach and navigate through the different layers and I think you'll understand. If anyone has some idea it would be great... 

Thank you