UPDATE - Google has released a fix for this bug in version 63 of Google Chrome
There is a rare issue where Chrome users will intermittently not be able to use their microphones. When a user hits this, other meeting participants will not be able to hear them. This is a Chrome bug that Google is actively working on. More details for this issue and its progress can be found here.
To clear the issue you have to completely quit Chrome and relaunch it. Please note, completely quitting means closing out all Chrome tabs, not just one. Instructions on how to do this are below.
On Mac, you can completely quit Chrome by going to the Chrome menu in the top left and selecting “Quit Google Chrome”
On Windows, you can completely quit by clicking on Chrome in the bottom windows bar and clicking “Close All Windows”