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:
“The average Ph.D. thesis is nothing but a transference of bones from one graveyard to another.”
—J. Frank Dobie (1888–1964)
“The mastery of one’s phonemes may be compared to the violinist’s mastery of fingering. The violin string lends itself to a continuous gradation of tones, but the musician learns the discrete intervals at which to stop the string in order to play the conventional notes. We sound our phonemes like poor violinists, approximating each time to a fancied norm, and we receive our neighbor’s renderings indulgently, mentally rectifying the more glaring inaccuracies.”
—W.V. Quine (b. 1908)
“Reduced to a miserable mass level, the level of a Hitler, German Romanticism broke out into hysterical barbarism.”
—Thomas Mann (1875–1955)