1. Input Barrier Dimensions & Source & Receptor Positions (m)
2. Input ABS Barrier height. Whiswall is set at 1.1 m
3. Choose Source Input (Other allows you to put in your own spectrum)
4. WHIS®top and Low-F WHIS®top are 20 cm and 10 cm tall, respectively. To evaluate the effect of adding them to an existing barrier, choose YES.
5. This is a simple approximation for the performance of the diffractors. This does not, in any way, substitute the full Dutch Calculation Method.

Introduction

• This spreadsheet is a tool for comparing the acoustic performance of different diffractors, such as the WHIS®wall and the WHIS®top, to an idealized noise barrier.
• We have assumed as the baseline, an absorptive noise barrier with zero reflection and zero transmission
• The barrier and diffractor performance are based on the published Dutch noise calculation and measurement method, used in the commercial software Geomilieu from DGMR.
• The Dutch calculation method assumes a source height of 0.75 m for road traffic. In this tool, it can be set to any chosen height. 4Silence recommends the use of 0.1 m source height, as it validates well with our measurements.
• The WHIS®top and Low-F WHIS®top are 20 cm and 10 cm tall, respectively. To evaluate the effect of adding them to an existing barrier, then the overall height should be raised by such amount.

Comparison Tool

• Input – (1) Noise Barrier height, (2) Source height, (3) Receptor Height, (4) Source to Barrier Distance (5) and Barrier to Receptor Distance (6)
• Elevated Noise Barrier performance can also be simulated by inputting negative Receptor Height values

Traffic Spectrum

• Select a source spectrum to use in the calculation
  This allows the user to select the 1/3 octave spectrum shape (from 100Hz to 5KHz) to use in the calculation
  ROAD : Based on the Dutch noise calculation and measurement method and used on DGMR Geomilieu software. With this option, the user is able to enter speed and intensity for light (LV), medium (MV) and heavy (HV) vehicles.
  RAIL : EN 16272-3 : The normalized traffic spectrum for the rail traffic noise barriers. (Note this is only used for product performance certification and not in noise studies)
  NMPB : This is a typical shape of the road traffic spectrum used in the French Road Noise Prediction Method – NMPB. (Note, UK CRTN method is purely broadband based)
  CNOSSOS : This is a typical shape of the road traffic spectrum used in European Metohd – CNOSSOS. (Note, UK CRTN method is purely broadband based)
  OTHER : Allows for a user-defined spectrum. (Note – The default value the measured Pass by noise used in the M&P whiswall study August 2020)

Performance

• The calculated results are presented as an attenuation difference (dB)
• The calculated results are also presented as total attenuation difference (dB) by the diffractor + barrier in comparison with no barrier at all.