I'm adding to my post below of things I've discovered about the crackling sound issue. I take it back that I'm running Windows 11. I'm on Windows 10 Pro. I'm running an Intel Core i5-8600K CPU @ 3.60GHz. My husband's machine, which runs the game perfectly fine, though with lower graphics since I have a better video card, is an AMD Ryzen 7. It's a much newer processor with more cores and threads. His is also not able to be upgraded to Windows 11, so it's still a pretty old processor. So, I have a new processor and motherboard on order. Yeah! I've been wanting one for a while.
I did learn something very interesting last night. I went and updated my chipset drivers, the Realtek chipset drivers from the motherboard manufacturer, and my BIOS (which was woefully out of date). And...the problem is nowhere near as bad! The game was nigh on unplayable anywhere but the lighthouse and the crossroads. Now, there is a little stutter, but nothing that I can't live with. Still have the new processor and board on order: new case too, (back connected - yeah!). But, I think the problem boils down to the processor and chipset. All 3 of the DXDiags that people have put down in the comments have been old processors: 2 i5s and a Ryzen 3. Check your processors to see if you're one of the ones that are on the list, but still a little old. I am wary of saying to flash your BIOS and update your chipset drivers, because that can be some advanced technical stuff, but it worked for me.