I have had experiences where I will clearly hear someone I know like my mother or a friend's voice call my name and when I turn around there is no one there. It is so audiable. I think Ghosts do not whisper I think it depends on their strength of communication to our plain. They are on a higher plain and the communication may just come through as a whisper to us when they just might be speaking normally. I think they know our names because they have heard people call us by that name and because since they are dead they are by default just more intuitive