This could be a 2 edge sword.

How long until the Police departments are sued for unlicensed public performance of copyrighted music?

Rather, why isn’t software available yet for end users to filter out copyrighted background noises?

There is software like Spleeter [1] that can split songs into stems (seperate drums, vocals, rhythm, etc.) using ML. I imagine it would be possible to adapt it for this. Might even work as-is if you only needed to isolate people's voices.

1. https://github.com/deezer/spleeter