If you hear audio echo or audio feedback during your meeting, there are three possible causes:

• A participant has both the computer and telephone audio active.
• Participants have computer or telephone speakers that are too close to each other.
• Multiple computers with active audio are in the same conference room.

For more information, visit the link below.

https://support.zoom.us/hc/en-us/articles/202050538-Audio-Echo-In-A-Meeting