The publicity in La Gazette Musicale du Nord for the Télépiano, a Coupleux invention from 1922, left me puzzled. You can see a lady playing the piano (the transmitter) while some people are sittting elsewhere listening to another piano (the receptor). The music was seemingly delivered along telephone lines. An article about this invention clarified a lot: the receptor piano was simply a piece of furniture with no piano mechanism in it, just an amplifier. So the ‘receptor’ could in fact have any form. For example that of a … speaker?
The Coupleux brothers from Lille, France and their extraordinary inventions are described in the book ‘1900-1935 L’aventure industrielle des frères Coupleux’, by Olivier Carpentier.