@sepples No idea as I've never need a use for anything like that, as I don't usually have mics to listen to me on my computers and when I do, I just adjust the mic to fix any noise issue.

ALSA supports plugins, so it's a matter of adding a noise suppression plugin in addition to the current ones; https://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html