Bobby Owsinski

“This imaginary image can sometimes shift as the balance of the music shifts from side to side, which can be very disconcerting to the listener, especially if the speakers are placed far apart. As a result, film sound has always relied upon a third speaker channel in the center to keep the sound anchored. This format is called LCR, for Left, Center, Right, and it became a staple of multiplex movie theaters and high-end home video setups where the center speaker is located near or behind the screen. This third channel never caught on in consumer music circles however, mostly because people had a hard time finding a place for two speakers, let alone three.”
― Bobby Owsinski, The Mixing Engineer's Handbook: 5th Edition