I am pretty new to the harp in general; I've been playing about a year. On Led Zeppelin IV, the song when the levee breaks, what is that sound? I'm a rank amature so I can't tell if it's amplified harp, which would be awesome because I would love to be able to play that some day. Or if it's slide guitar; if it is slide, how would you approximate that sound on harp. Thanks in advance -Brandon