How do I check if a specific command is playing sound?

Title. I'm trying to come up with a bash script that starts playing gregorian chants when a live stream is not playing sound. And to stop playing when the live stream stars playing audible sound again. Maybe something that monitors the volume of a specific command? I've no idea, honestly.

Being a bit more specific... the live stream is being played via ffplay/yt-dlp and I'll use mpv to play the gregorian chants. Alsa.Thanks in advance.