Digital sound level meters are commonly used in noise pollution measurement for the quantification of different kinds of noise, especically for industrial, environment and construction sites.
IEC 61672-1 standards divide sound level meters into two "classes". The two classes have the same functionality, but different tolerance for error. Class 1 instruments have a wider frequency range and tighter tolerance than low cost, Class 2 unit. Class 1 sound level meter is employed for research, NEA requirements and law enforcement.
Refer to The National Evironment Agency for Noise Pollution Regulation.