mic on USB webcam sounds like evil robot chipmunk after upgrade

[inscrutable-g]

Hey All,

Long time reader, first time poster. I just performed a long overdue upgrade from Mint 17.2 to Mint 20.2 (Cinnamon, 64 bit). Everything is mostly good (although I have, in the process, learned that my 5 year old machine is not really up to the challenge of modern software) except for one thing: the Logitech C210 USB webcam with integral microphone that I use for video calls, and which was working just fine before the upgrade, now makes me sound like an evil robotic chipmunk 4 out of every 5 times I use it. I thought at first that it might be an interaction between Zoom and Firefox but it also happens on Google Meet (even if run it on Chromium) and on Signal Video (which requires no browser at all). Once, I noticed that Meet gave me the option of choosing one of two versions of my webcam microphone and one worked while the other did the evil chipmunk thing but that only happened once, haven't seen the option since then.

I've searched the forums as well as I could but couldn't find anything that matched my problem. Any ideas would be greatly appreciated.