Simplified analytical model for sound level prediction at shielded urban locations involving multiple diffraction and...

Area of Science:

• Acoustics
• Urban planning
• Computational physics

Background:

• Urban noise mapping requires accurate prediction of sound fields in obstacle shadow zones.
• Existing methods for predicting sound propagation in complex urban environments can be computationally intensive.

Purpose of the Study:

• To develop and validate a simplified, efficient model for predicting sound levels in shielded urban locations.
• To incorporate multi-edge diffraction and multiple reflections into the urban sound propagation model.

Main Methods:

• The model is based on Pierce's diffraction theory, approximating the Fresnel Integral with trigonometric functions.
• It is parameterized for urban environments and validated against Pierce's theory and full-wave numerical methods.
• An efficient approach using the Hurwitz-Lerch transcendent is employed for mirror sources and receivers.

Main Results:

• The simplified model shows deviations less than 2 dB compared to full-wave simulations for octave bands (125-1000 Hz) in idealized urban configurations without canyons.
• Larger errors occur when receivers are near the diffraction edge extension.
• Accuracy comparable to full-wave simulations is achieved when incorporating the Hurwitz-Lerch transcendent for reflections.

Conclusions:

• The proposed simplified model offers an efficient and accurate method for predicting urban sound fields in shadow zones.
• This approach is valuable for generating detailed and reliable urban noise maps.
• Further refinement may be needed for scenarios with receivers very close to diffraction edges.