Amplifiers; antenna boosters; antennas; signal distribution devices; antenna distributors for audio communication; video signal distributors; transmitters of electronic signals; telecommunications transmitters; sound transmitting apparatus; receivers of electronic signals; telecommunication receivers; sound receiving apparatus; audio tuners; radio signal tuners; audio signal interfaces; audio signal transmission and reception devices; network audio transmission and reception devices; audio signal converters; network audio devices; telephone apparatus; telephone transmitters and receivers; intercom systems; intercom exchanges; intercom stations; infrared communication systems; audio signal processors; audio mixers; loudspeakers; public-address (PA) systems and instruments; megaphones; emergency broadcasting equipment; public address (PA) and sound system accessories; public address (PA) and sound system accessories and fittings, namely, microphone stands, speaker stands, microphone cables, speaker cables, connectors, mounting racks, cabinets (for loudspeakers) and installation brackets thereof; mounting racks for telecommunication devices and apparatus; mounting racks for sound system devices and apparatus; mounting racks for closed circuit television system devices and apparatus; cabinets for telecommunication devices and apparatus; cabinets for sound system devices and apparatus; cabinets for closed circuit television system devices and apparatus; storage container boxes exclusively for use in racks and cabinets for broadcasting machines and apparatus; blank panels exclusively for use in racks and cabinets for broadcasting machines and apparatus; ventilation panels exclusively for use in racks and cabinets for broadcasting machines and apparatus; loudspeaker associated components; installation brackets for telecommunication hardware; installation brackets for sound system devices; installation brackets for closed circuit television system devices; protective carrying cases specially adapted for wireless microphone systems; earphones; microphones; radio microphone systems comprising microphones, tuners and receivers; sound reproduction apparatus; audio recording and playback devices; audio and video receivers; video signal receivers; synchronized video signal transmitting devices; video signal interface devices for closed circuit television system; video signal transmission and reception devices; video display switching devices; video signal compensation devices for closed circuit television system; hard disc drives; digital video recorders; video signal converters; network video monitoring devices; radios; electric installations for the remote control of industrial operations; electro-dynamic apparatus for the remote control of signals; controllers for speakers; control panels for public address systems; audio signal controllers; control panels for the operation of video equipment; controllers for video monitoring equipment; monitors for audio equipment; attenuators; electrical transformers for telecommunication apparatus; audio frequency transformers for public address (PA) system; programmable timers for use with public address (PA) systems and broadcasting machines and apparatus; battery chargers for microphones; conference systems comprising telecommunication devices and apparatus; electronic bulletin boards; closed circuit television systems; closed circuit television cameras; lenses for closed circuit television cameras; covers for closed circuit television cameras; electrical swivels for closed circuit television cameras; housings for closed circuit television cameras; electric monitoring apparatus; video monitors; electric plugs, outlets, jacks and connectors for audio frequency machines and apparatus and video frequency machines and apparatus; computer software, recorded; computer software for use in recording, amplifying, reproducing and transmitting sounds; downloadable computer software; pre- recorded sound recording media; electric cables and wires; audio and video signal cables; electric or magnetic meters and testers: impedance meters; phonographic records