Electrical, electronic, signal and monitoring apparatus, namely, electroacoustical instruments and parts thereof, namely, RF receivers, RF input modules; apparatus for receiving, transmitting and reproducing audio signals and parts thereof namely, radio transmitters, high-frequency audio receivers, high-frequency input modules, for providing sound balance; apparatus for recording and reproducing electrical signals, namely, sound signals, namely digital audio tape recorders; apparatus for wireless transmission of acoustic information, namely, wireless microphone transmitters, plug-in microphone receivers; electroacoustical and visual, identifiable guide systems comprised of sound signal receivers, audio transmitters and headphones for providing verbal information in single or multiple language format for use in museums, exhibitions, theatres, and other public events; apparatus for broadcasting, transmitting and receiving sound signals or video signals, namely, high frequency sound transmission apparatus such as pocket transmitters and pocket receivers, namely such pocket radio transmitters and pocket audio receivers for UHF and VHF ranges, diversity audio receivers and small audio receivers, live news coverage apparatus, namely, broadband radio transmitters with command audio receivers, backward channel radio transmitters, diversity program audio receivers, and command radio transmitters; antennas; apparatus for narrow-band and broadband systems in sound transmission engineering, namely, radio transmitters, pocket radio transmitters and pocket audio receivers; radio transmitters, namely, multichannel radio transmitters and single-channel radio transmitters, infrared radio transmitters; audio receiver, namely, multichannel, single-channel and two-channel audio receiver; headphone audio receivers; chin-strap audio receivers; apparatus for sound transmission and sound reproduction, namely, infrared and high-frequency audio transmitters and audio receivers, namely, audio mono-receivers, stereo audio receivers, two-channel audio receivers, and chin-strap audio receivers; connectors for listening and speaking devices, namely, adaptors; instruments for communications engineering systems, namely, communications headsets and headphones for use in conferences and simultaneous translations, all areas of telecommunications, airlines and air traffic control, news reporting and military communications; microphones with integrated transmitters, namely, condenser microphones with built-in high frequency transmitters, soloist microphones, pressure microphones, switchable microphones, interface microphones, electret microphones, headset microphones, gooseneck microphones, directional tube microphones, wireless microphones, clip-on microphones; microphone parts, namely, microphone diaphragma capsules, omni-directional electret microphone capsules, omni-directional foil electret capsules, microphone modules effected through computer aided acoustic design and laser interferometry techniques, microphone terminal distributors, and microphone sleeves namely sleeves for protection of wind, sweat, and spit; electroacoustic transducers, namely, headphones, dynamic headphones, electrostatic headphones, wireless headphones, headphones for use in aircraft, busses and trains, namely, with infrared transmission or high frequency transmission, headphones and headsets with and without active noise compensation, and loudspeakers; parts and accessories for electroacoustic transducers and headphones, namely, ear pads, volume controls, amplifiers, namely high-end and tube amplifiers, batteries, battery chargers, and cable connectors