Consider this expression
Dude, have you seen that song? It is insane.
Obviously saying 'heard' in place of 'seen' make more sense, but over here what I want to ask is Have you heard about the song not exactly hearing the actual song?
Consider this expression
Dude, have you seen that song? It is insane.
Obviously saying 'heard' in place of 'seen' make more sense, but over here what I want to ask is Have you heard about the song not exactly hearing the actual song?
Have you heard about the song?
is correct. It means you know about it from a news report or someone told you about it. It does not assume that you have actually heard the song.
Once you actually hear the song, you can say
I heard that song.
I don't think seen makes any sense in this context (other than possibly a music video or performance).
Any time someone addresses me as dude, I assume the question is informal. In the context of a music video or viewing the title on the charts - the song being the title, not the actual play - 'Have you seen that song,' would be permissible. Although, better options would be 'Have you seen the video of that song,' or 'Have you seen that song title on the charts?"