Could you try this:
Open Control Panel.
Open Sound.
Click the Recording tab.
Double-click on the microphone you are using in the list of recording devices:
Click the Levels tab.
Click the microphone icon, shown muted below: The icon will change to show as unmuted:
Click Apply, then OK.
source: https://help.webex.com/en-us/WBX81342/A-Yellow-...
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