## 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.