As of yesterday, my audio got stuffed up. Whether on release candidate or the stable version, I had the same thing. I can mainly hear my car, though it cuts in and out. Can't hear other cars at all. I didn't fancy deleting my whole player.json and setting up all my preferences again, but I solved it by going into that file (...SteamLibraryJ\steamapps\common\rFactor 2\UserData\player\player.JSON) and deleting all of the audio stuff, i.e. from "Sound Options" to the end of the file. [edit: don't delete the very last }, otherwise the file is unreadable by rF2] When I restarted rF2 the game loaded up and all my preferences were as previously. Not the audio ones, obviously, as they had reset to default.
What you did was corrupt the player.json manually. Just as if there was a CTD when rF2 was trying to exit while it wrote new data to the player.json file. So when Steam next loaded rF2, it downloaded a clean copy of the player.json. This is one of our standard fixes when rF2 suddenly decides not to work. (delete or rename the player.json and sometimes the entire player folder.)
Release Candidate is randomly changing number of effects (audio) to 1. It won't randomly change itself back. So that's the more straightforward fix next time - set it to 64. @davehenrie sounds like it perhaps complained but then fixed the file, rather than starting a new one. Also the game just creates the JSON files - no downloading involved.
Thanks Lazza. I've edited my first post, as actually if I don't delete the final bracket '}' then there is no warning message when I start the game and the audio is fixed. Next time I'll just set my audio effects back to 64. Worth noting that this happened again to me today, even though I'm still on the stable (non-RC) build. So it isn't just the RC that is messing with me.
I am wondering if this value has changed from 32 to 64 recently. I did not have the issue, yet someone in our server last night did. I went to show them how to fix while looking at my settings and noticed mine were at 32.
I think 32 has long been default, and I'm not even sure (myself) that the default has changed. But if you're there and changing it, might as well go 64 - rare that system these days can't do it