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GP-82-3 <br />NOISE TERMINOLOGY <br />Ldn; Day-Night Average Level. The average <br />- equivalent A-weighted sound level during <br />a 24-hour day, obtained after addition of <br />1Q decibels to sound levels in the night <br />before 7 am and after 10 pm. <br />Leq: The energy-equivalent level is <br />- a steady noise having the same <br />given time-varying noise., Tfie <br />represents the decibel level o <br />value of sound energy or sound <br />squared. The L is the noise <br />used to calcula~~ the CNEL. <br />A-Weighted Sound Level: <br />that level of <br />energy as a <br />L thus <br />E ~~e time-averaged <br />pressure <br />descriptor <br />The decibel measure of the sound level utilizing <br />the "A" weighting network of a sound level <br />meter is referred to as "dBA". The "A" <br />weighting is the accepted standard weighting <br />system used when noise is measured and <br />recorded for the purpose of determining <br />total noise levels and conducting statistical <br />analyses of the environment so that the output <br />correlates well with the response of the <br />human ear. <br />Note: CNEL and L represent daily <br />levels of noise e~~osure averaged on an <br />annual basis, while L represents <br />the equivalent energye~oise exposure for <br />a shorter time period, typically one hour. <br />5/19/82 <br />