Ok then, time for a subsumtion. A majority of five users assumes the sound having natural causes. A minority of two users, Pensaboy and me, is convinced that this doesn't sound natural, where Pensaboy seems to be experienced in playing and recording the guitar.
User "ustas" seems to be in favor for not starting any more discussion, maybe because it is obviously not an error or the topic is not important enough. Do the other "naturalists" join ustas?
If not, I would like to take the idea of Pottel to ask Guy Fletcher, just to make sure.