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:
“You preferred it to the usual thing:
One dull man, dulling and uxorious,
One average mind—with one thought less, each year.”
—Ezra Pound (1885–1972)
“the children call, and I
Thy shepherd pipe, and sweet is every sound,
Sweeter thy voice, but every sound is sweet;
Myriads of rivulets hurrying through the lawn,
The moan of doves in immemorial elms,
And murmuring of innumerable bees.’”
—Alfred Tennyson (1809–1892)
“Why level downward to our dullest perception always, and praise that as common sense? The commonest sense is the sense of men asleep, which they express by snoring.”
—Henry David Thoreau (1817–1862)