GP1 (my DDs first boar) used to purr in a really rumblestrutty way (but didn't move himself) when she played the theme to "Animal Crossing" on her DS Lite. It's like an Indian sitar. He went into a 'trance' almost when the music was on 
DH was watching an old Dr Who (on the Horror Channel) , a Tom Baker one. There was a very synthetic bird noise repeated. GP5 moved her head left-to-right over and over then fixed me with her weirdy ruby eyed stare until it came on again, then more head moves. 
Her eyes look just like clear red glass, no ligamenty bits. so she completely spooks me.