Sound Level Meter NSLM-100 is a simple, portable measuring device which is widely used to test the sound level of the environment, machinery, vehicles, music, ships and other noises. It is equipped with a 1/2-inch electret condenser microphone that quickly determines the sound intensity and converts it to an electrical signal, which is displayed on a well-lit LCD. These meters, also known as decibel meters, are mandatory for environmental monitoring as well as for measurement of all workplace noise parameters.