What is the "Number Above" noise metric?

The "Number Above", also referred to as N-level noise metric or Count Above, is the total number of aircraft operations that exceed a specified sound level threshold. The MAC publishes N-level information in the monthly MSP operations reports, including a count of departure events and arrival events when the maximum sound level of those events exceed 65, 80, 90, and 100 dB levels. 

Updated 4/16/2017