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Lden Calculation


Lden definition


What is the Lden (Day-Evening-Night Level) in Acoustic Calculations?


The Lden indicator (Level day-evening-night) is a critical measurement used in environmental noise assessments. It represents the weighted average noise level over a 24-hour period, accounting for varying noise sensitivities during different times of the day.

Formula to Calculate Lden:

\[ Lden = 10 \log_{10} \left( \frac{1}{24} \left( 12 \times 10^{\frac{LAeq(6h-18h)}{10}} + 4 \times 10^{\frac{LAeq(18h-22h)+5}{10}} + 8 \times 10^{\frac{LAeq(22h-6h)+10}{10}} \right) \right) \]

  • LAeq (dBA): The equivalent continuous sound pressure level over a specific period (T).

Understanding the Lden Components:

As shown in the formula, noise levels are adjusted to reflect higher sensitivity to noise in the evening (by adding 5dB) and at night (by adding 10dB). This adjustment helps to better represent the impact of noise pollution on people during these periods.

For more detailed information, visit our pages on exterior noise calculation and explore our acoustic product database.

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