I've also got Windows 11 and no problems here I'm afraid.

Do you have a surround sound set up? (5.1/7.1). If so check the centre speaker settings as there might be a mix option or something like that in your audio card settings. All cutscene voice for this game comes through the centre speaker and usually when people say about voice issues, it's to do with surround sound/centre channel not being set up correctly.