[...] What determined the rapid development of Electroacoustics was its relationship with telecommunications. Thus, the so-called electroacoustic chains were created, the links of which constitute, in the acoustic part, the medium of propagation between the primary source, the receiver, and the electroacoustic transducer (the audio-electric, taking into account the direction of energy transfer), such as an open space, a residential room, a classroom, a cinema, a concert hall. [...] (from the introduction of the book)