Type B uncertainty in sound power measurements using comparison method

A model for estimating the uncertainty of sound power measurements using a standardized comparison method was developed accordingly to ISO-GUM, and its Type B budget is presented herein. As it does not depend exclusively on the noise source under measurement, but also in other controlled variables, such as equipment setup, data rounding and environmental conditions, its use and evaluation is of most importance to achieve lower uncertainty values. The model was applied in a set of sound power determination of a family of household appliances (blenders), and it was found to be 0.2 dB(A) (k = 1) in average. Comparing the results obtained with the literature and experimental results, it is possible to conclude that both Type A and Type B uncertainties are important in a complete estimation of sound power uncertainty of a particular family of sound sources.