The paper presents a case study of noise generation and its reduction as applied to a three phase induction motor. Noise patterns of electric motors are of complex nature due to the different sources that are involved. Each of these sources can be detected from the noise spectra. These sources are mainly mechanical, electromagnetic and aero-dynamic sources. As the author was involved in research investigation dealing with the mechanical noise sources,some experimental results are also presented giving the effects of changing the bearing pre-loading,clearances and the bracket stiffness on the noise level of the test motor.