Day–evening–night noise level

The day–evening–night noise level or L{{sub|den}} is a 2002 European standard to express noise level over an entire day. It imposes a penalty on sound levels during evening and night{{cite book|author=Malcolm J. Crocker|title=Handbook of Noise and Vibration Control|url=https://books.google.com/books?id=46NvrvpHIxEC&pg=PA15|date=5 October 2007|publisher=John Wiley & Sons|isbn=978-0-471-39599-7|page=15}} and it is primarily used for noise assessments of airports, busy main roads, main railway lines and in cities over 100,000 residents.{{cite web|url=https://www.umweltbundesamt.de/daten/umwelt-gesundheit/gesundheitsrisiken-durch-umgebungslaerm|trans-title=Health risks from environmental noise|date=2 June 2020|title=Gesundheitsrisiken durch Umgebungslärm|publisher=Umweltbundesamt}}{{cite book|author=Daniel R. Raichel|title=The Science and Applications of Acoustics|url=https://books.google.com/books?id=bKml0CXdkzEC&pg=PA331|date=4 January 2006|publisher=Springer Science & Business Media|isbn=978-0-387-26062-4|page=331}}{{cite book|author1=Norman J. Ashford|author2=Saleh Mumayiz|author3=Paul H. Wright|title=Airport Engineering: Planning, Design, and Development of 21st Century Airports|url=https://books.google.com/books?id=-V_yKCO592EC&pg=PA724|date=6 April 2011|publisher=John Wiley & Sons|isbn=978-1-118-00547-7|page=724}} The penalty for sound production during evenings and nights is due to higher nuisance perception during quieter hours and to prevent sleep deprivation for nearby residents.