Check your firewall has been suggested, but also check your anti-virus. Make sure the game is on the list of exceptions. Verify your game cache just in case it's a corrupt audio file or issue with a game file. Valheim is small so won't take long to verify.

Check your sounds with the game running. Alt-tab to the desktop and right click your speaker. Check under both your sound settings and volume mixer to make sure the game sound is turned up and that the game has the correct sound device selected. In the sound settings you need to go to the advanced options section (scroll down a bit) and select the app volume and device preferences option. Then you can pick which specific devices are being used for Valheim.

Originally posted by LinkStrife:

Once you get the sound going, you'll want to turn off the music so you can better hear the deer. Very soothing.

I do recommend you turn the music off, or way down, so you can hear all the other sounds in addition to the dulcet tones of the deer. BLARRRRT!!!!

Seriously though, turn the music down for a while and listen to the sounds around you. The sound design is quite good.