No audio if more than one person unmuted

[DavePoole]

We use Zoom to run morse code lessons.

When we join the meeting we can all hear each other.

I take the Host, mute and start sharing a morse code program or webpage to send the code.

When the code is finished, I reveal the code that was sent, unmute and sometimes I cannot be heard until I stop the share.

More lessons are sent and then usually we have more audio problems. If more than one person is unmuted we cannot hear each other. We have to get each person to unmute to speak and all others muted or we cannot hear.

Does anyone have any hints of what we can do to overcome this?

We have to have background suppression set to low to enable the morse code to be heard and all our mics and speakers are working fine when we join the meeting, it is only after screens have been shared that the problems appear.

[ZoomTestKitchen]

I would recommend enabling "Original Sound". 

1. It Disables Zoom Noise Suppression
2. Removes High Pass Filtering
3. Removes Automatic Gain Control

It basically lets the original sound be transmitted without filtering it.

Beyond original sound I would set some guidelines for the attendees.

1. When they attend they are in a quiet environment. This is due to the suppression being turned off.
2. When they attend they wear over the ear or earbuds, and do not use open speakers. Same reason behind it.

Once you feel like you've got control of the audio, you can then see if you can get by with enabling "Echo Cancellation" for those just in case moments when someone shows-up with open speakers.