Near-field Acoustic Holography (NAH) applied to localize sources on a geared electric motor


In order to optimize the noise emitted from a wide range of products, e.g., vehicles, mechanical components, and electric appliances, identifying the most important noise sources on the test object offers a very important engineering value. Determining the position and frequency content of the noise sources enables the user to find the root cause of the problem, while ranking of the sources can be used to decide where the noise reduction effort should be concentrated in order to improve the overall noise radiation most effectively.


An experiment on a geared electric motor is presented in this application note to demonstrate how to use OROS Air Holography software to localize and quantify noise sources. The measuring procedure which enables both the spatial resolution and upper frequency limit to be doubled, without additional hardware, is described. The NAH approach is first validated by locating two known sound sources. Then several unknown sources are identified, and the results are consistent with the outcome of the modal analysis using OROS Modal solution. In the end, the noise sources are ranked, indicating where the mechanical changes should be focused in order to reduce the overall noise effectively.

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