CEL-621 Digital Environmental Sound Level Meter

Environmental noise measurements use statistical parameters to charactarise the level of environmental noise. These parameters are called Ln%, where the n represents a percentage from 0.1 to 99.9. For example, the L₉₀ (normally L_AF90) is referred to as the background noise. So if the L_AF90 = 38dB, then the noise level was above 38dB(A) for 90% of the time. Different Ln values are required to be measured for different environmental noise legislation. Typical standards involved are BS4142, ISO1996, PPG24, BS7445 and many others. The CEL-621 is ideal for short term environmental noise measurements where the overall Ln levels are required as opposed to logging the Ln values over time where a CEL-490 should be used.