Not absolutely sure whether this is a hardware or software problem. Just looking for a starting point for where to look first.
Running on an old Dell Optiplex computer, I5-2400 2nd gen, so you know it’s a decade old. That said, I had Mint on it previously, Sound had worked without problems and had just installed Manjaro on it two weeks ago. My wife tried to use it for a Zoom meeting recently, post install, and couldn’t get anyone on the Zoom call to hear her, though the sound from the other participants was not affected. She could hear everybody through her headphones. I checked her headphones on my computer and on a test Zoom call worked reliably both in listen and talk, so I ruled that out.
Thinking as old as her computer is, maybe the on motherboard sound chip was failing, so I just purchased a USB outboard sound chip which gives additional USB connectivity as well as its own sound chip. Same Problem.
So either it’s somewhere deeper in the hardware on the motherboard somewhere, or it’s a software problem. What’s the next step?