Specifying and measuring the noise level of electric motors in operation

A sound intensity noise testing approach specifically for rotating electrical machinery is described. The method achieves accurate results in the presence of other noise sources and in acoustical environments that are suitable for noise testing via conventional procedures. Tests have been performed on actual motors to demonstrate the method, and results are presented to illustrate its validity. It is concluded that loaded motors can be successfully tested for noise output, and it is urged that IEEE noise testing standards be expanded to cover the testing of loaded machines, including use of the sound intensity method