We also use WebEx at work (university setting) and for smaller meetings, we require everyone to use (at a minimum) a set of basic headphones to avoid echo. If

We also use WebEx at work (university setting) and for smaller meetings, we require everyone to use (at a minimum) a set of basic headphones to avoid echo. If they don't use them, they need to keep their mic muted whenever they aren't speaking. For class-related stuff or larger meetings/seminars, we use the Events portion of WebEx instead of Meetings. It's basically the same thing, but there are more "roles" so there's a host who can mute/unmute participants or assign privileges. Panelists are the speakers who can turn their audio and video off by themselves but can only screen share if made a "presenter". Attendees are just the people watching the thing, and they can chat with text but can't turn their own mics on. They can raise their hand or the host can find them in the attendee list if they need to unmute them. Once people got used to how it works, it has been surprisingly effective. You don't need to make sure every attendee in a 300-person seminar has headphones on--just the people who are presenting. If one of the presenters is unwilling or unable to use headphones, I can mute them if they have a live mic that's just causing echo while they sit there and listen. Students and other attendees can still speak with their mics, but only when called on. Incidentally, this also does away with all of the issues of people disrupting Zoom calls because you can only join as a panelist if you are on the list and have the right link. You can still publish the attendee link publicly because the worst thing an attendee can do is type in the chat (and even then, they can only send to "all participants" if you enable it).