Protective helmets; sound protective helmets; amplifiers; noise reducing apparatus; apparatus to actively reduce sound and vibration levels; earphones, telephone apparatus and receivers, microphones; loudspeakers, cabinets for loudspeakers; acoustic conduits; acoustic couplers; diaphragms (acoustics); transmitters of electronic signals; apparatus for recording, transmission or reproduction of sound; sound locating instruments; printed circuits; data processing apparatus; computers, calculators, calculating machines; electrical and electronic measuring apparatus; electrical and electronic sound and vibration measuring instruments and apparatus; wavemeters; radios; audio receivers; speaking tubes

Development and design of computer software for scientific research; technical studies; research on acoustics; appraisal services; surveying; rental of computers, measuring apparatus and computer software