Hello tealsirens
I was wondering if you already tried the following:
> Right-click the Speaker icon from the Notification Area.
> Click Sounds.
> Go to the Recording tab.
> Select your microphone from the list.
> Click Properties.
> Go to the Listen tab.
> Uncheck the Listen to this device box.
> Click OK on both the opened boxes and try again.
I am not sure if you already tried the above solution, but if you did, please confirm what other troubleshooting suggestions have you followed and what were the results so we can offer you with a precise solution.
Cheers!!