Akoustik Engineering Limited performed a thorough noise source identification (NSI) analysis for Gold Corp Canada Ltd. to identify and control significant noise sources of 785B haul trucks. The purpose of the NSI analysis is to identify the significant noise contributors and recommend abatement solutions to reduce the overall sound power level of the 785B haul trucks and reduce the environmental noise impact. NSI is a highly technical analysis that can accurately identify significant noise sources through the use of beamforming. Beamforming uses an array of microphones to identify the origin of noise and generate a contour map to display the source of significant noise emissions. Measurements of 785B haul trucks were taken using Brüel & Kjær 30-channel pentangular array and Brüel & Kjær 60-channel circular array. The first phase of testing was of a stationary 785B haul truck and the 30-channel pentangular array revealed that the significant source of vehicle noise was originating from the front grill of the vehicle. With the source of the major noise contributor identified, a custom designed louver was recommended to Gold Corp by Akoustik to control the noise source.
In the second phase of testing, pass-by measurements of the 785B haul trucks were the core interest. These measurements recreated the worst-case scenario of noise emission during regular operation of the vehicles. Tests were conducted for a haul trucks with and without the custom louver. Using the 30-channel pentangular array to record pass-by measurements, an NSI analysis was conducted. For greater resolution, the refined beamforming calculation method was used and significant noise sources were identified. In addition, a second stationary test was conducted with the 60-channel circular array for both trucks. The 60-channel circular array is used for close range measurements, which in turn has a higher resolution. The haul truck was divided into sections and several measurements were taken of each section to map the entire vehicle. With a contour map of noise emissions from the vehicle, significant noise sources were identified. It was concluded that the custom louver was proven to reduce the noise emission originating from the front grill. With follow up measurements the noise abatement process is still ongoing to unveil the optimal noise abatement treatment.