In this work, the production and perception of noise from technical equipment is presented. As a case study, the noise of switched reluctance machines (SRM) was used. The principle of operation of SRM is presented as well as the characterization of some noise problems of electrical machines. The measurement results from the motor surface vibration and the directivity of the radiated sound from the machine are discussed and some noise optimized control strategy for a SRM are shown, with an example of what is achievable and which are the limits of such strategy. The concepts of tonalness and consonance are defined and some theories behind them are described. The results of exhaustive psychoacoustic listening test about the perceptual characteristics of the noise of a technical source are presented, analyzed and discussed. The main conclusions of the listening tests are: One important component of the perceived annoyance of technical sounds is the tonalness. Different tonalness calculation algorithms are in agreement with the results from the listening tests. The consonance/dissonance of technical sounds depends on several parameters, i.e. roughness and frequency ratio.