Hello, thank you for reaching out to Microsoft Q&A.
May I please know whether you are using any headset or earphones plugged in? Also, do you have any third-party audio management software installed?
We can try reinstalling the audio drivers once and see if it makes any changes to the audio output when the microphone is in use.
- Open the Device Manager.
- Expand the arrow next to sound, video and game controllers.
- Right-click your default audio driver - Realtek (R), select uninstall device, select 'Attempt to delete the driver software for this device check box' and then click Uninstall.
- Once uninstalled, restart your computer and test it.
Let me know how it goes.