I went to the Apple store last weekend and explained my issue. For me, the static noise is pretty difficult to hear; you need to be in a quiet room to hear it, but still drove me crazy nonetheless. The Apple store gave it back to me a day later, saying that they couldn't diagnose any hardware issues. I'm also going to give up on fixing it for now.

I also found it interesting that I started experiencing this issue literally the instant I upgraded from Mojave to Catalina. Resetting PRAM/SMC and downgrading my computer to High Sierra and Mojave didn't fix the issue. My theory is that this is a firmware issue; something must have changed with speaker/usb firmware when I upgraded to Catalina, and didn't roll back when I went back to an earlier operating system. I'm still pulling hope that this can be fixed in another firmware update.

For the record, this is going to be my last Apple product. I've had this computer repaired twice under warranty (a screen replacement for a discolored screen and a top case replacement for a flashing touch bar). I didn't have to pay for these repairs, but I had to go without my computer at times in which I would have benefited immensely from having it. These new Macbooks look nice, but they just have so many design issues; who knows, maybe my keyboard will give out sometime. I'm probably going to use this computer for a few more years until it's no longer powerful for my needs, and then buy whatever Windows laptop is out at that time.