Environmental Noise Directive EU

Overview

Engineering reference data for Environmental Noise Directive EU in acoustics.

Key Formulas

Speed of Sound

$c = \sqrt{\gamma R T}$

Speed of sound in an ideal gas.

Sound Level

$L = 10 \log_{10}(I/I_0)$

Decibel level.

Wavelength

$\lambda = c / f$

Wavelength = speed / frequency.

Variables

Permissible Noise Levels by Area Type

The EU Environmental Noise Directive specifies permissible cumulative exposure levels (Lden) for different area types:

Time Period Definitions

The directive defines standard time periods for noise assessment:

• Day time (td): 07:00 - 19:00 (12 hours)
• Evening time (te): 19:00 - 23:00 (4 hours)
• Night time (tn): 23:00 - 07:00 (8 hours)

These periods are used for calculating the day-evening-night noise indicator (Lden).

Day-Evening-Night Noise Indicator Formula

The cumulative 24-hour noise exposure indicator Lden is calculated using:

$$L_{den} = 10 \log_{10} \left[ \frac{1}{24} \left( t_d 10^{L_d/10} + t_e 10^{(L_e + 5)/10} + t_n 10^{(L_n + 10)/10} \right) \right] \quad \text{dBA}$$

Where:

• $L_d$ = Day exposure level (dBA)
• $L_e$ = Evening exposure level (dBA)
• $L_n$ = Night exposure level (dBA)
• $t_d$ = Day time period (typically 12 hours)
• $t_e$ = Evening time period (typically 4 hours)
• $t_n$ = Night time period (typically 8 hours)

Interactive Charts

References

• Original Source