Electrical apparatus for recording, transmitting and reproducing sound, in particular microphones, microphones that also function as loudspeakers, earphones, loudspeakers, all also being remote controlled; wireless and non-wireless transmitting and receiving apparatus wireless, manufactured electrical cables, power supply boxes, voltage transformers, voltage regulators, electrical amplifiers, connection panels, apparatus for control, apparatus for calculating, memory units, microprocessors, control desks, control panels, keys, commutators, indicators; electrical connectors for the aforesaid goods; cases, housings, frames, desks and tripods for the aforesaid goods; components for all the aforesaid goods; installations for language interpretation and group discussion composed of combinations of the aforesaid goods