There is a bug with the dialogue audio in The Witcher 3 Wild Hunt, most commonly occurs when using headphones, where you can hear the background music super loud however cannot hear what the characters are saying.
Enable Windows Sonic for Headphones
- Open the Sound settings control panel;
- Right click on the speaker icon in the taskbar and click on the Sound settings in the context menu.
- Open the Properties menu for your Output device;
- Left click on your Output device to open up the Properties menu.
- Select ‘Windows Sonic for Headphones’ option for the Spatial audio settings.
- Settings should take effect immediately otherwise, you may need to restart the game.