My brother used to have a really cool four track 45 from Sennheiser in Germany that was recorded using a single set of their mic elements placed where the ears are on a dummy's head. The end result was a type of recording called "binaural". When you wore headphones and listened to the disc, you heard the recorded performances as if you were there at the actual event! The disc had four musical performances, with one of them being a circle of singers with the dummy's head placed in the center of them.