Voice-over course examples

Greetings, Heroes! 

I am researching best ways of introducing voice-overs to entire courses, with the caveat that the course has to remain accessible. My Storyline 360 solution is to have a "read" button on each slide which will activate the voice-over at user's will rather than have it kick-in automatically. With this, there are some problems and questions: in this case the button will also have to appear on each of the layers in case of a tab interaction; will it interfere with JAWS reading the course; should the button toggle between play and pause?

Do you have any outstanding examples of a short course with full voice-over solution? I would really appreciate, 

Thank you!

Darya