While you're at it, always display a vu-meter. It gives feedback on what is transmitted and thus can alert a user whether they are being heard or not. It's the most basic of sound recording tools, and was a standard part of recording equipment for over half a century for good reason.

And if you need minimalism, offer a toggle for that. But I think most people should have it forced on them, would save anyone a lot of trouble -- just think about all the aggregate time lost talking into a muted mike by all users.