Electrical, electronic and optical measuring, signalling and monitoring apparatus, instruments and devices insofar as included in class 9, in particular electrical devices and instruments in electroacoustics and parts thereof, devices and instruments for recording audio signals and parts thereof, insofar as included in class 9; microphones, filters (insofar as included in class 9), mains power-supply units, electroacoustic transducers, headsets, ear phones, loudspeakers, amplifiers, hearing aids; battery charge devices, parts of the aforementioned goods insofar as included in class 9; devices for the transmission of audio and video signals, transmitting and receiving devices, in particular wireless transmitters, pocket transmitters, diversity receivers, antennae, devices for audio transmission, devices for speech therapy, infra-red transmitters and receivers, instruments in communications engineering, operator telephone handsets, the aforementioned goods also with active noise compensation, sound-proofing devices, in particular in headset form; receiving devices for recording and reproducing electrical signals, in particular audio signals, devices for the wireless transmission of acoustic information, data carriers provided with programs, in particular diskettes, tapes and disks; cables; audio devices and instruments and parts of all aforementionted goods insofar as included in class 9