Apparatus and instruments for measuring, registration and monitoring of sound and vibrations and hardness, namely, vibration meters, electro-technical vibration meters, sound and vibration analyzers, acoustic analyzers, electro-acoustic analyzers, structural dynamics analyzers, data acquisition amplifiers, conditioning amplifiers, hand-held vibration analyzers, sound level meters, noise dose meters, noise monitoring terminals, electroacoustic transducers, microphones, hydrophones, electrical ...