Gilbert, on a windows system each file type is represented by an icon, but that icon is defined not by the file type itself but by the default program the computer uses to open/play it

so in your example you show mp3 with the icon that windows 10 uses if it opens/plays by default with windows media player [a blue note on white background]

if you sent that to me it would show on my system as an icon that is an orange and white striped cone, because it would open by default in VLC media player - and because wav files and mp4 files and lots more also open by default in this player, they all will show the same icon

this is the way it works - the icons are not part of the file, they are part of the OS