Cortana cannot hear me - But my microphone works fine everywhere else

Solution 1:

Go into settings>change sound card settings>recordings>choose your mic>go into levels and slide the volume to the needed level. This worked for me.

Solution 2:

Mentioned solutions doesn't work for me, but following does:

  1. Right-click on the sound icon in the taskbar, and go to Recording devices
  2. Double-click on your default microphone
  3. Go to Enhancements, and check Disable all sound effects (seems like in oldest version of windows 10 the option is Disable all enhancements)