Only a few people can communicate in coference, and the rest of the people (guest) could only listen and chat. How to do this?

[ghost]

I want to make a video conference in which there will be 4 or 5 speakers. And the invited guests could only observe (listen and see) and comment on the conference.

In the /etc/spreed/webrtc.conf file, I activated
^ conference /.+ =

Now everyone who receives the https: // domain / conference / conf-chatroom link
automatically turn on in conference mode.

Can you please tell me how to do this, so that only a few people can communicate, and the rest of the people could only listen and chat?