I heard the pulsars' sounds on a show on the history channel that talked about the freaks in space (or something like that).
I'm not sure how they get the sound. I think it comes from radio waves (I'm pretty sure that's what they said on the show). They played a bunch of different ones on the show while they were talking about them.
Also the Bat For Lashes song has it at beginning of the "Two Planets" song ... or something that sounds like what I heard on the tv. (Does this help sister?:D )