Day–evening–night noise level explained

The day–evening–night noise level or L 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.

Definition

L is calculated as:^[5]

L _{den} = 10 ⋅ log _{10} \left( (1)/(24) \left( 12 ⋅ 10 ^{(L _{day})/(10)} + 4 ⋅ 10 ^{(L _{evening} +5)/(10)} + 8 ⋅ 10 ^{(L _{night} +10)/(10)} \right)\right)

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

Part of the day	hours	penalty (dB)
day	07:00 - 19:00	0
evening	19:00 - 23:00	5
night	23:00 - 07:00	10

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

The formula for L 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

Notes and References

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