Some sound systems (including mine) have a separate center speaker and on some discs the dialogue is recorded on the center channel so I can up the dialogue volume independently of the rest of the soundtrack. It's a nice feature but is dependent on the formatting of the soundtrack.
That's something I didn't know. In the early days of stereo, they loved to greatly vary the left and right channels, so the music was swirling around from ear to ear which was a truly cool experience! Music would be too flat if it's the same in both ears.
If you ever get to Chicago the Museum of Science and Industry has a captured WWII German U Boat, the U-505. I was surprised at the amount of wood work there was inside the sub.