Apparatus and instruments for recording, transmission and reproduction of audio signals and parts thereof, included in this class; apparatus for recording and reproduction of electrical signals, in particular audio signals; apparatus for the remote transmission of acoustic information; receivers, in particular multi-channel, single-channel and dual-channel receivers, infrared receivers and radio receivers, headphone receivers, stethoset receivers and parts for the aforesaid goods; apparatus for sound transmission and reproduction apparatus; headsets; software, in particular on CD-ROMs, DVDs, hard drives, floppy disks and volatile and non-volatile memories; microphones, in particular dynamic microphones, condenser microphones, electret microphones, headset microphones, gooseneck microphones, shotgun microphones, wireless microphones, clip-on microphones, microphones having integrated transmitters, in particular condenser microphones having integrated radio transmitters, microphone modules, pressure microphones, switchable microphones, microphone capsules and parts for the aforesaid goods; microphone cases; electroacoustic transducers, in particular headphones, dynamic headphones, electrostatic headphones, wireless headphones, headphones for use in vehicles and aeroplanes, in particular having infrared or radio transmission, headphones having active noise compensation, loudspeakers, including wireless loudspeakers; parts and accessories for electroacoustic converters and headphones, namely, ear pads, volume controllers, repeaters, battery plugs, plug-in chargers, handset cords; electro-acoustic and visual identifiable guide systems, including multi-lingual guide systems, consisting of transmitters, receivers, in particular sound signal receivers and headphones; apps (software) for controlling sound recording and reproduction apparatus; apps (software) for recording and reproduction of audio signals