The day-night average sound level (Ldn or DNL) is the average noise level over a 24-hour period. The noise between the hours of 10pm and 7am is artificially increased by 10 dB. This noise is weighted to take into account the decrease in community background noise of 10dB during this period.
The Federal Aviation Administration has established this measure as a community noise exposure metric to aid airport noise analyses under Federal Aviation Regulation Part 150.
Famous quotes containing the words average, sound and/or level:
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—Thomas Carlyle (1795–1881)
“He hath a heart as sound as a bell and his tongue is the clapper, for what his heart thinks, his tongue speaks.”
—William Shakespeare (1564–1616)
“The truth is, that common-sense, or thought as it first emerges above the level of the narrowly practical, is deeply imbued with that bad logical quality to which the epithet metaphysical is commonly applied; and nothing can clear it up but a severe course of logic.”
—Charles Sanders Peirce (1839–1914)