Day–evening–night noise level

The day–evening–night noise level or L_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[1] and it is primarily used for noise assessments of airports, busy main roads, main railway lines and in cities over 100,000 residents.[2][3][4] 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.

Noise level map of the surroundings of Amsterdam Airport Schiphol

Definition

L_den is calculated as:[5]

${\displaystyle L_{den}=10\cdot log_{10}\left({\frac {1}{24}}\left(12\cdot 10^{\frac {L_{day}}{10}}+4\cdot 10^{\frac {L_{evening}+5}{10}}+8\cdot 10^{\frac {L_{night}+10}{10}}\right)\right)}$

Where the long-term average noise levels are defined as:

Part of the day	hours	penalty (dB)
day	6 - 18	0
evening	18 - 22	5
night	22 - 6	10

The exact hours of the three periods may be chosen differently by individual EU member states.

The formula for L_den can be considered a weighted average of the yearly individual noise level during day, evening and night.

See also

• Environmental noise directive
• Day-night average sound level, the US equivalent

References

1. Malcolm J. Crocker (5 October 2007). Handbook of Noise and Vibration Control. John Wiley & Sons. p. 15. ISBN 978-0-471-39599-7.
2. "Gesundheitsrisiken durch Umgebungslärm" [Health risks from environmental noise]. Umweltbundesamt. 2 June 2020.
3. Daniel R. Raichel (4 January 2006). The Science and Applications of Acoustics. Springer Science & Business Media. p. 331. ISBN 978-0-387-26062-4.
4. Norman J. Ashford; Saleh Mumayiz; Paul H. Wright (6 April 2011). Airport Engineering: Planning, Design, and Development of 21st Century Airports. John Wiley & Sons. p. 724. ISBN 978-1-118-00547-7.
5. "Directive 2002/49/EC". Act of 25 June 2002.