Error: Why can't a person be heard in a meeting?

Someone has muted themselves: This can be recognised by the fact that the microphone is displayed in red in the user overview on the left-hand side. Simply click on the microphone icon in the middle of the conference.
Someone has joined without a microphone. This can be recognised by the fact that a headphone symbol is displayed next to the name instead of a microphone. Here you have to log out of the meeting and select the microphone icon when joining the meeting again.
Someone is using Chrome or Firefox on an Apple device: In this case, please check in the browser's settings under Preferences/Privacy if the browser has permission to share the microphone.
Is the correct microphone selected? The browser line often shows when access to the microphone is granted, there you can also determine by clicking which microphone is to be used. For example, if someone has connected a headset to the laptop, the changeover to the new microphone does not always happen automatically.
Is the microphone in the system muted or very quiet? This error happens more often with Windows 10. In this case, users can go to the Windows settings (Control Panel) and look for the microphone settings in the "Sound" menu. There, one can select the correct microphone and adjust the input volume.