Sound level meter
A sound level meter (or sound meter) is a device used to measure sound pressure levels. It is often used to study and measure different kinds of noise, especially industrial and transport noise. The display indicates sound level in decibel units.
Sound Level Meter Media
An integrating-averaging Cirrus Research's Optimus sound level meter which complies with IEC 61672-1:2002
Noise monitoring station at Muir Woods National Monument in California