1004 59TH PL SW 2016-01-01 MF Import

Noise Assessment: Broadway Apartments Project Michael R. Yantis Associates Inc., P.S. Page y Another noise descriptor is the Equivalent Noise Level (Leq), which is the dBA level of a constant sound which has the same acoustical energy as the time-varying noise. The EPA describes it: "The equivalent sound level is a single value of sound level for any desired duration, which includes all of the time-varying sound energy in the measurement period". Therefore, a sound that was 60 dBA for ten minutes, and 70 dBA for ten minutes would have an Leq for the total time period of 67 dBA (remember, logarithms do not add together directly). It can be seen that the higher level sounds are weighted heavier in the calculation, because they have more energy. The Ldn, or day-night equivalent sound level, is the Leq measured over a 24 hour period, with a 10 dBA penalty applied to night-time levels (10:00pm to 7:00am).