Is It Shirk And Kufr To Listen To Hindu Mantras?

I mean listening to Hindu mantras with the intention that it will have some effect on someone or yourself. As far as I know black magic is a part of hindu religion, so I would like to know if listening to such thing with the intention that it might effect us in some way (positive or negative). If it is indeed Kufr or Shirk, then how does a person repent from it?