Measuring and scaling the unpleasantness of PV-inverter sound emissions based on psychoacoustic metrics

PV inverters produce noise emissions which can generate complaints from people when installed in buildings. At present, however, there is no adequate measure to estimate sound annoyance caused by PV inverters. To assess the annoyance generated by inverter noise emissions, basic measurements and listening tests were performed and a measure for the annoyance – unpleasantness - was scaled. Because the A-weighted sound pressure or sound power level in dB(A) does not account for the subjective impact of noise characteristics, psychoacoustic metrics such as loudness, sharpness and roughness were analysed and correlated with the scaled unpleasantness. The results show that a linear combination of (binaural) loudness, roughness, and sharpness metrics account for more than 90% of the variance in unpleasantness ratings, whereas A-weighted sound pressure level and other purely acoustical measures of sound power or sound pressure performed poorly in this respect. Especially the influence of the cooling fans cannot be represented by this measure. Thus, a reliable measure and test method may be developed to scale and predict the unpleasantness of PV-inverter noise emissions, providing the designers with a measure to improve the sound emissions of PV inverters during the development process. Customers and planers, on the other hand, would be able to choose inverters suitable for different locations inside a building