Pairwise comparison psychoacoustic test on the noise emitted by DC electrical motors

In this paper, the noise emitted by cheap DC electrical motors is investigated by means of a one-to-one comparison psychoacoustic test. This is because, nowadays, DC electrical motors are widely used, and it is useful to understand the main causes of acoustic annoyance. In particular, though different DC electrical motors are fed with a power generator whose voltage is kept constant, their noise emissions are different, indicating various emission spectrums. Since a spectrum is characterized by many harmonics related to the rpm of motors, one of the main problems is finding a method to understand how these harmonics are related to sound quality parameters and, therefore, acoustic annoyance.Two descriptors of sound quality, roughness and pitch height, have been studied. Furthermore, the manner in which roughness and pitch height affect the annoyance is investigated.Results of this study can help manufacturers and users discard motors on the basis of their noise before being sold or installed.