If you are experiencing this issue while playing the game through Steam, please try deleting all files in the "SteamLibrary\steamapps\common\Mount & Blade II Bannerlord\Sounds" folder and then validate your game files by right-clicking the game in your Steam Library and selecting "Properties... > Local Files > Verify integrity of game files..." If the issue persists after this it would help us greatly if you could reach out to us here and let us know.