Love this idea. I also thing there is a great use case here for people in sales, customer support / onboarding. Listening as a skill is very important for roles like this, and anything that can help people be a bit more conscious about this is great.

A top bar icon for this could also be useful, so not to take up too my screen real estate, e.g. for example if you are giving a sales demo, you may want to hide the application, but still see visually how you are doing.