City Noise Map: Visualizing Sound Propagation in Urban Environments

What is a City Noise Map?

A city noise map is a representation of sound levels in an urban environment. It helps us visualize the distribution of noise from various sources such as roads, railways, and aircraft. This tool provides insights into how different factors like geometric spreading, air absorption, ground effect, and building and barrier diffraction influence these sound levels.

The map also includes hourly sound levels and the EU day-evening-night level (Lden), which is a weighted average of daytime, evening, and night noise levels. This metric helps in assessing compliance with environmental noise regulations.

Key Acoustic Principles

The propagation of sound through the atmosphere involves several key principles. Geometric spreading occurs as sound waves spread out from their source, reducing intensity over distance. Air absorption reduces sound levels further by converting some of the acoustic energy into heat. Ground effect can either amplify or dampen sound depending on the surface properties and the frequency of the sound.

Barriers such as walls and hedges can significantly reduce noise levels through diffraction, where sound waves bend around obstacles. This principle is crucial in designing effective noise barriers along highways and railways.

Real-World Applications

Understanding city noise maps is essential for urban planning and environmental management. By analyzing these maps, planners can identify areas with high noise pollution and implement strategies to reduce it. This includes designing sound barriers, adjusting traffic patterns, or even changing the layout of buildings.

The Lden metric is particularly useful in assessing long-term exposure to noise, which can have significant health impacts such as sleep disturbance, stress, and cardiovascular disease.

How Does It Work?

The simulation models the propagation of sound from various sources using mathematical equations. For example, the inverse square law describes geometric spreading: the intensity of a sound wave decreases with the square of the distance from the source.

Air absorption is modeled by incorporating frequency-dependent attenuation coefficients that account for the conversion of acoustic energy into heat as it travels through the air.

Frequently asked questions

Try it live

Everything above runs in your browser — open City Noise Map: Road, Rail and Aircraft Sound Levels with Barrier Diffraction and Lden and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.