Features:
Bar-graph display 
Data storage and data hold 
Measuring level selection and time weighting level selection. 
Max/min reading. 
Backlit display

Applications:
Sound level meters are commonly used in noise pollution studies for thequantification of different kinds of noise, especially for industrial, environmentalmining  and aircraft noise.

Measuring Principle:
Sound level meter measures the sound level in logarithmic scale. There is a diaphragm in the microphone which responds to changes in air pressure caused by sound waves. This sound pressure is converted into logarithmic scale and displayed.