Apparatus and instruments for acoustic and vibratory measurements, namely, acoustic meters, vibration meters, noise dosimeters, sound level meters; stand-alone instruments and devices for monitoring and predictive maintenance of machines, namely, micro-processor based hardware and software used to monitor the status of industrial machinery; micro-processor based hardware and software linked to a communication network for monitoring and predictive maintenance of industrial machinery; micro-processor based hardware and software used to monitor the status of variable-speed or cyclical-operation machines and to predict the maintenance of variable-speed or cyclical-operation machines; data acquisition and processing micro-processor based hardware and software used to monitor the status of variable-speed or cyclical-operation machines and to predict the maintenance of variable-speed or cyclical-operation machines; multi-channel protective monitoring devices, namely, micro processor based hardware and software to trigger the shut down of rotating machines; real time and sequential monitors for monitoring the availability status all for machines and strategic sensors; real time and sequential monitors for monitoring the availability status all for fixed-speed and variable-speed machines and strategic sensors; real time and sequential monitors for monitoring the availability status, all for machines on plain bearings, journal bearings and antifriction bearings and for strategic sensors; computer software for use in storing, analyzing and tending machine data in the field of machine predictive maintenance and vibratory analysis; computer software for use in storing, analyzing and tending machine data in the field of machine predictive maintenance; computer software for use in storing, analyzing and tending machine data related to machine vibrations