2011 Volume 35 Issue 4 Pages 331-339
The numerous machines used in public works projects produce noise simultaneously. For practical noise prediction the noise emitted by each machine must be quantified. Analyses have been done by microphone array and delay-and-sum, but the error of the analyzed values from smaller power sources is large because the measured values are influenced by the emissions from larger power sources. The error remained unresolved in the previous report. In this report, we discuss the virtual counter sound source (VCSS) method, which hypothesizes virtual sound sources to erase the larger power sources and then analyzes the sound pressure from the smaller power sources, as an original solution. Simulations clearly show that the VCSS method fundamentally improves the accuracy. And the improvement of the accuracy has been confirmed by the analysis of the experimental data in a semi anechoic chamber.
