Towards a unified system of noise assessment

Abstract

Different indices are in current use for expressing the nuisance value of successions of noises, according to the type of noise. It is shown that a single index, termed noise pollution level, accommodates the experimental results of surveys of aircraft and of motor vehicle noise. The same formula satisfactorily explains the results of laboratory tests in which noise intensity is traded against duration to maintain equal impressions of objectionableness. The index is based on two terms, one representing the equivalent continuous noise level on the energy basis, and the other representing the augmentation of annoyance when fluctuations of noise level occur. Practical and theoretical implications of the index are discussed.