Profile: Monitor Instruments, Inc. manufactures industrial audiometers and audiometric accessories. We also offer calibration services for audiometers and acoustic safety equipment. The MI-7000 microprocessor audiometer is designed for hearing conservation programs. It is well suited for either stationary or site to site testing. The MI-3000 audiometer is an economical, manually operated audiometer that tests frequencies from 125 Hz to 8000 Hz, including standard interoctave frequencies.