Criteria for assessment of noise annoyance

Day-night average sound level (DNL) and the relationship between DNL and community annoyance to noise are often presented to a community as part of a noise-assessment process, usually as established scientific fact. In reality, there is great scatter and variability in the attitudinal survey data that are the basis for the DNL-response relationship. As a result, there is significant uncertainty around the corresponding curves that are fitted to the data. This paper collects, tabulates, and compares recommended minimum DNL criterion levels for various types of communities and settings. The paper summarizes some of the recommended adjustments to DNL that are contained in ISO 1996-1:2003 and other factors that reduce the variations between predicted and reported community noise annoyance. The paper recommends that the appropriate DNL criterion level in residential areas should be between 50 dB and 55 dB. Differences between attitudinal survey data on community annoyance and predicted community responses can be minimized by use of adjustments, most of which are contained in ISO 1996-1:2003.