Evaluating tonal noise in the outdoor environment

Abstract

Most outdoor noise criteria are based on the overall A-weighted sound pressure level evaluated at one or more location(s) on the receiving property. The maximum allowable sound pressure level is usually based on the zoning or actual use of the source and receiving properties. The referenced levels are often the Leq and/or the Lmax measured over a defined time interval, although the L(n) percentile statistical levels are sometimes specified. It is a well-known fact in the acoustics community that broadband sound at a given level is less annoying than sound with strong tonal components at the same sound pressure level. As a result, many state and local governments have included tonal penalties in their environmental noise ordinances to help compensate for this tonal annoyance factor. This presentation identifies several state and prominent local governments that have imposed such a penalty and how the government has elected to assess the presence of a tone that would warrant such a penalty.