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:
“One cannot develop taste from what is of average quality but only from the very best.”
—Johann Wolfgang Von Goethe (1749–1832)
“I am afraid that the animals regard man as a creature like themselves which has lost its sound animal wits in a most dangerous way—that they regard him as the deranged animal, as the laughing animal, as the weeping animal, as the unhappy animal.”
—Friedrich Nietzsche (1844–1900)
“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)