Hey! Sorry to hear you're having issues
First off, if you're closing in on having more than two hours play time due to fixing this bug,
consider asking Steam for a refund! It's automatic as long as you've played less than two hours. After you get a refund, you can download the demo later on to see if it works, without the risk of losing money.
Anyways: I'm suspecting that something is crashing the sound engine, which makes the game shut it off rather than crash. This has the unfortunate side effect of "hiding" the error message, however. I'll have to add an in-game command that checks the status of the sound engine and prints errors related to it... but that doesn't help you in this exact moment.
It's a bit of a long shot since you reinstalled the game already, but you could try verifying the cache in case there is a corrupt sound file. (Right click on game in library, select properties, go to Local Files and then click Verify Integrity of Game Cache)
Also, if you check the volume mixer in windows, does the sound bar belonging to the game move at all, or does Windows also report the game as completely silent?