Opera Communications
In 1881 Telephones and microphones the Bell system were installed at the Opera.
Electric bells There aas a system of bells called Sprung bells that originally alert servants in large mansions that their masters needed them in another part of the house. In the Opera house electric bells and 61 call buttons were installed in various parts of the building by M. Boivin. For the administrative service the ringing of these bells establishes communication between the Managing Director's office to the offices of the different heads of the different departments.
Voice tubes, Sound tubes/ tubes acoustiques : which was a long pipe by means your voice could be transmitted though cones on either end it early version of the intercom. Each end could be fitted with a little alarm which whistled to get the other ends attention before speaking. Only one person could speak at a time. A technology thought to be first invented in the late 1700's and was mostly used in bourgeois houses, businesses, and on ships. Mr. Boivin installed a system of more than 300 meters of acoustic tubes, communicating from the chandelier, the cupola and the first deck to the gas organ in the Paris Opera.
Le Nouvel Opéra by Charles Nuitter, 1875