Predicting and assessing the distribution and impact of noise in urban environments through noise simulation (i.e., noise maps)

The increasingly severe urban traffic noise pollution is becoming visible, manageable, and controllable through a digital approach. In the simulation of urban elevated rail transit noise, research found 3.5 Meter-high sound barriers can reduce noise 9 on floors and below 5-8 decibels, but 17 above these floors, the noise reduction effect is basically lost. Fully enclosed sound barriers perform excellently, providing noise reduction at heights of 1-30 floors, with the maximum noise reduction reaching 16 decibels.

This precise conclusion does not come from traditional field measurements but from the application of noise simulation technology. Through SoundPLAN and other professional software, engineers can build urban acoustic environment models on computers to accurately predict noise distribution and propagation patterns.

What is a noise map?

Conventional methods for monitoring road traffic noise are fast and simple but lack important source data and meteorological parameters, are affected by background noise during measurement, and have limited monitoring points. A noise map is a digital map created through noise simulation that can predict the noise distribution of an entire area in the future, enabling real-time updates and dynamic management. It can obtain the number and distribution of people directly affected by noise at different times, providing scientific basis for noise control planning and construction project approval management. Noise maps are based on mathematical models and acoustic algorithms, converting real living environments into abstract mathematical models for automatic calculation. Calculation types include noise contour maps, color scale maps, building surface sound pressure level distribution, and specific point noise calculations.

Technical core: How does SoundPLAN work?

SoundPLAN Software Since 1986 year by Braunstein+Berndt GmbH was released, it quickly became the standard outdoor acoustic software in Germany and gradually became the leading software worldwide for noise prediction, mapping, and evaluation. The modeling, calculation, and evaluation of this software are based on ISO standards and relevant national standards, including "Technical Guidelines for Environmental Impact Assessment - Acoustic Environment" ( HJ2.4-2009 ). SoundPLAN It uses a sector model for sound field calculation. Starting from the receiver point, it emits "rays" covering all areas and entities to be considered, including sources, reflectors, sound barriers, ground attenuation zones, etc.

The ray interval is usually set to 1 degrees (default value) but can be set manually. The smaller the interval, the more accurate the calculation, but the slower the calculation speed. Studies show that sector scanning is much more accurate than ray scanning because it covers the entire area around the receiver point, while ray scanning ignores parts between rays.

Application examples:

✨ Urban traffic noise control

In a study in Luohu District, Shenzhen, researchers used SoundPLAN Software to generalize and model 18 main urban roads and surrounding features, and adjusted parameters based on actual monitoring data to draw a noise distribution map of main roads in Luohu District. They modeled Binhe Avenue, Binhe Middle School, and surrounding terrain and found that the first row of teaching buildings had serious noise exceedances both during the day and at night. Simulation results showed that after installing a bent sound barrier with a length of 200 meters and a height of 5.0 meters along the auxiliary road, the daytime noise on each floor of the first row of teaching buildings was reduced by 2.4 ~ 6.7 decibels. The study also estimated that the number of people directly affected by noise along the road accounted for more than 50% of the total population at sensitive points.

✨ Rail transit noise simulation and evaluation

Noise measurement of elevated rail transit lines is time-consuming and labor-intensive, with limited data obtained, and new projects cannot be measured before sound barriers are installed. This makes noise simulation an important method for evaluating the effectiveness of sound barriers.

A study used SoundPLAN Software to simulate the effects of sound barriers and additional noise reduction measures, comparing 5 types of sound barriers. The results showed that 2 meter low arc-shaped sound barriers, compared to upright sound barriers of the same height, performed better overall because the arc-shaped barriers are closer to the source and create a larger shadow zone. Fully enclosed sound barriers have significantly better noise reduction effects than other barriers, providing noise reduction at heights of 1-30 at heights of

✨ floors.

SoundPLAN Application in industrial noise control SoundPLAN Software It also plays an important role in industrial noise control. In a semi-indoor substation noise control case, researchers used

for solid modeling to predict horizontal and vertical noise distribution. The study pointed out deficiencies in noise protection due to the layout of the semi-indoor substation and determined the vertical noise impact range of the main transformer on surrounding high-rise buildings. By analyzing noise diffusion patterns of main transformer air intake louvers of various sizes, the study found that the larger the louver size, the farther the noise spreads horizontally and vertically through the louvers, and the wider the impact range.

Technical limitations and challenges SoundPLAN Although SoundPLAN Software and other noise prediction software are powerful, they have certain limitations. A study pointed out that due to differences in road conditions and vehicles, under the same traffic volume, SoundPLAN Noise prediction software cannot account for sound wave interference, resulting in calculated outcomes that differ significantly from measured sound fields. This indicates that although noise simulation software offers powerful predictive capabilities, it still needs to be combined with actual measurement data to achieve more accurate results.

Future Development Directions

Noise simulation technology is continuously evolving and improving. With advancements in computing power and algorithm optimization, the accuracy and real-time performance of noise maps will keep improving. Researchers in Luohu District, Shenzhen, have pointed out that the next step could involve more detailed investigations, collecting more comprehensive data to enhance the precision of noise simulations, refining noise maps to better reflect real conditions, and providing technical support for noise control and environmental management. However, due to current legal and regulatory limitations, as well as simulation accuracy issues, noise simulation results cannot yet be directly used for administrative enforcement. This necessitates further research and standardization to enhance the authority and reliability of noise simulation technology.