I'm very sorry. I was not thinking about people who have a disability or impairment. As others have pointed out, as long as the person without a mic is willing to listen then things can be done. Its just much quicker for people to confirm their role if they are able to speak on the mic. There are some people who have no hearing or speaking difficulties and simply just don't want to help the team by communicating in the fastest, most efficient and most effective manner.