Ask yourself - (A) can no one hear you? Or (B) is it only some people that cannot hear you?
(A) No one can hear you
This might be because your mic is muted. Observe the mic icon in the bottom of the webinar studio:
(A) Crossed over icon: You are muted, press the icon to unmute yourself. If not possible test another mic device in the list.
(B) When talking you cannot see the mic icon moving: Your mic might not be audible, please confirm that you are audible with a colleague or switch mic input.
(B) Only some people cannot hear you
This might be due to:
Them having muted the video player. Guide them to move the mouse cursor or tap the video box to bring up the video box menu. In the menu there is a speaker icon, and make sure it's not muted.
They should also make sure they are able to play audio from their device at all - ie. they have speakers or headphones connected.
Context:
Univid is completely browser based. This is great, as the attendees do not have to download anything and it's a smooth experience - but also means that there are some minor restrictions the browser enforces.
Most of the times auto-playing audio is fine. But if the attendee, have some very strict browsers or settings changed, they might have to click the interface to activate audio.