I know this is in flux, so this is an observation, not a bug. The volume for most sounds in general, including the background music, was lower than usual for me on login. I checked my audio settings and I had most things set to around 70% level. I turned up everything to 100 (except background music, just nudged that up), and the sound volumes were back to what I was used to.

Except when I was digging up antiquities. The "whoosh" when you completely uncover an antiquity was the same, but for every other sound (digging, etc.), the volume was too low.