In certain situations (like Q&A sessions), a member of your audience will need to be heard by the whole room. In order to enable your attendees to speak when they are in the audience tables, follow the steps below.
Click on the avatar that you want to enable
Click the settings cog and then simply click "Offer Public Mic", which will ask the user if they would like to accept the invitation.
Once they accept the microphone will turn from a mic icon into a yellow megaphone icon along with an alert at the top of the screen.
Once they are finished simply remove the access from the user putting them back to speaking only to their table.
Note: Anyone who is on stage will automatically be switched to the public mic, this will change once they return to their table.