The evaluation of uncertainty in environmental acoustic measurements according to the ISO ‘Guide’

The evaluation of uncertainty associated with environmental acoustic measurements is often underestimated, despite its fundamental importance in assuring measurement quality, particularly in noise certification of cars, trucks, aircraft, household equipment and when measured values must be compared with those imposed by authorities. In this work, the general matter of expressing the uncertainty of environmental acoustic measurements, according to the ISO Guide to express uncertainty in measurement has been studied with respect to identification, classification and treatment of the main sources of uncertainty. The application of the ISO procedure to some meaningful examples (obtained by traffic, railway and industrial noise measurements) are discussed. It is shown that a suitable evaluation of different components of uncertainty associated with sound pressure level measurements and the application of the normalised ISO procedure to express them are fundamental to ensuring the reliability and usability of measurement results.