[ Laboratory furniture; Protractors; Amplifiers and pre-amplifiers used to control feedback; ] Electroacoustic transducers; Electronic sensors for measuring sound; [ Artificial electroacoustic transducers for sight and hearing; ] Electroacoustic transducers for electronic and cybernetic automatons; [ Electronic sensors for the determination of positions and distances for use in robots; ] Three-dimensional electroacoustic transducers; Laboratory equipment and supplies, namely, reflectors of el...