Hi @mariacleh7
Do you have more than one device connected to the meeting - like a laptop and desktop, or a laptop and mobile device? That might be one cause.
Or - one of your other participants may have open speakers, and an open (un-muted) microphone, and either their Echo Cancellation off, or their "Original Sound" ON. That would mean their microphone is picking up your voice and sending it back to you. But likely everyone else would hear an echo of themselves also. You could test for this by ensuring everyone else is muted, then see if you get the echo (with yourself un-muted).
Are other participants noticing an echo? How many participants do you have?
Or the other possibility is there is some sort of loop in your actual audio device locally. What are you using - built-in speakers/microphone, external headset, wireless anything?