BS EN 1793-4:2015

What is BS EN 1793-4- Sound diffraction of added devices in road traffic noise reducing devices about? 

BS EN 1793-4 is a standard that serves technical specifications for sound diffraction of added devices in road traffic noise reducing devices, enabling noise reduction in pedestrian road and traffic applications. 

BS EN 1793-4 describes a test method for determining the intrinsic characteristics of sound diffraction of added devices installed on the top of traffic noise reducing devices. 

BS EN 1793-4 test method prescribes measurements of the sound pressure level at several reference points near the top edge of a noise-reducing device with and without the added device installed on its top. 

BS EN 1793-4 method gives the acoustic benefit over a simple barrier of the same height; however, in practice, the added device can raise the height, and this could provide additional screening depending on the source and receiver positions. 

BS EN 1793-4 method has the following applications: 

• Preliminary qualification, outdoors or indoors, of added devices to be installed on noise reducing devices 
• Determination of sound diffraction index difference of added devices in actual use 
• Comparison of design specifications with actual performance data after the completion of the construction work 
• Verification of the long-term performance of added devices (with a repeated application of the method) 
• Interactive design process of new products, including the formulation of installation manuals 

BS EN 1793-4 test method can be applied both in situ and on samples purposely built to be tested using the method described here. Results are expressed as a function of frequency, in one-third octave bands between 100 Hz and 5 kHz. 

Who is BS EN 1793-4- Sound diffraction of added devices in road traffic noise reducing devices for? 

BS EN 1793-4 on sound diffraction of added devices in road traffic noise reducing devices applies to: 

• Manufacturers and suppliers of noise reducing devices 
• Dealers and importers of noise reducing devices 
• Contractors and infrastructure developers 
• Construction, civil and design engineers 
• Road maintenance authorities 
• Inspection and quality assurance services 

Why should you use BS EN 1793-4- Sound diffraction of added devices in road traffic noise reducing devices? 

Part of the market of road traffic noise reducing devices is constituted of products to be added on the top of noise reducing devices and intended to contribute to sound attenuation acting primarily on the diffracted sound field. These products will be called added devices. 

BS EN 1793-4 provides users guidance on sound diffraction index difference measurements, including dimensions and specifications, the position of sound source and microphone, free-field measurements, measured quantity and more, ensuring quality and operability of added devices. BS EN 1793-4 also provides users with a test method for determining the acoustic performance of added devices. BS EN 1793-4 also provides users with a step-by-step procedure for the method, enabling users to do the method correctly. 

The adoption of BS EN 1793-4 allows users to determine the sound diffraction of added devices, ensuring long term performance and compliance with required regulations. 

What’s changed since the last update? 

BS EN 1793-4:2015 supersedes CEN/TS 1793-4:2003, which is now withdrawn. 

Changes in BS EN 1793-4:2015 include: 

• The sound source positions have been reduced from six to four and are now all obligatory 
• The microphone positions have been reduced from 12 to 10 and are now all obligatory 
• A “free-field” impulse response to be measured for each microphone position and therefore, a geometrical spreading correction factor is no more needed in Formula (1) 
• Consideration of the measurement uncertainty has been added (Clause 5 and Annex B) 
• The summary of the test procedure (Clause 6) has been updated to reflect the changes compared to the previously published version