Trigger to play audio when other layers/audios have finished

Hi, I have an interection with five content layers, all with their own audio, and I want a final layer, also with its own audio to play once all five content items have been viewed/listened to.  Currently I have the content layers set up to play on clicking the relevant text descripition. Each text description has a second trigger converting its state to visited on clicking.  I then set up a slide trigger to show the final layer when the state of all 5 content layers = visited, but the final layer/audio plays  soon as the 5th text is visited and we dont get to see/hear the last item.  Is there a way to set this up so that learners can visit my 5 content layers in any order they choose, then automatically see/hear a final sum up layer at the end?