how to test your speaker audio out, microphone in, and camera in, for troubleshooting virtual meeting problems

in Windows 10

• audio out — Download stereo-test.mp3 from here.
• camera in — Use the "Camera" app that's already installed. Ctrl-F for "shell:AppsFolder" here for how to create a shortcut to it.
• microphone in — the "Volume Meter" app, by Bell Flare