Why is Marvel Rivals using the wrong microphone on PC?

Voice chat in Marvel Rivals is acting dead even though the headset works everywhere else. There is no clear error, and switching push-to-talk on and off does not change much.

What is the fastest way to separate a game setting issue from a Windows input-device issue? The game-specific side includes shader cache, fullscreen mode, voice chat, and frame-time spikes during team fights.

Do the device check in this order:

1. In Windows Sound, set the real headset mic as both Default Input and Default Communications Device.
2. In Privacy & security → Microphone, allow desktop apps to use the mic.
3. Close virtual audio tools and unplug unused webcams or controllers with microphones.
4. In Marvel Rivals, select the device explicitly instead of leaving it on “Default,” then test open mic and push-to-talk separately.
5. Disable exclusive mode for the mic in its Advanced properties if another app keeps taking control.
6. Restart the game after changing the Windows default; many games read the device only at launch.

Also check shader cache, fullscreen mode, voice chat, and frame-time spikes during team fights. Do not reinstall audio drivers until the mic fails in Windows Voice Recorder too.