Ader had arranged 80 telephone transmitters across the front of a stage to create a form of binaural stereophonic sound.[1] It was the first two-channel audio system, and consisted of a series of telephone transmitters connected from the stage of the Paris Opera to a suite of rooms at the Paris Electrical Exhibition, where the visitors could hear Comédie-Française and opera performances in stereo using two headphones; the Opera was located more than two kilometers away from the venue.[2] In a note dated 11 November 1881, Victor Hugo describes his first experience of théâtrophone as pleasant.[3][4]