Ever hear of something called “ghost vocals?” Once you listen to this, you won’t be able to unhear them.

Laughing Squid points us to this edition of the You Can’t Unhear This podcast that explains the concept of ghost vocals.

Anyone who’s ever heard Led Zeppelin’s “Whole Lotta Love” has sort of an idea of what this is all about towards the end of the song when Robert Plant starts wailing “Way down inside/Woman/You need/Loooooooooooooove.” A ghosty version of each line seems to precede the proper vocals. That, in fact, was a production error that sounded so cool the band decided to keep it.

That, however, was a phenomenon called “print through” which resulted from a reel of tape that was wound too tight for a little too long. The audio from one part of the tape “printed through” to the silent bit in the song one layer of tape down. Plant’s vocals and the silent parts just happened to sync up nicely.

That, however, isn’t what we’re talking about about. True ghost vocals are something else entirely. For more, let’s go to the podcast.