Abstract:

In order to estimate the noise radiated by an industrial facility, it is essential to accurately determine the far-field noise emissions of each piece of equipment. However, many times the only available equipment to determine acoustic information is near-field noise data. Therefore, accurate conversion of near-field to far-field noise data is necessary to determine equipment noise emissions at distant locations. This paper examines the process for converting measured near-field sound levels to far-field sound levels in actual equipment installations. Near-field data for various types of equipment are converted to sound power level and then extrapolated to a far-field sound level. The extrapolated sound levels are then compared to direct measurement data to verify the accuracy of near- to far-field calculations. The sensitivity of measurement results to environmental factors such as background noise and reflective planes is also addressed. The measurements and sound power level calculations are conducted in accordance with applicable ISO noise standards.