A systematic rationale for defining the significance of aircraft noise impacts.

Regulatory agencies often define strict, decibel-denominated thresholds of significance of noise impacts to protect some fraction of the residential population from exposure to highly annoying noise. Definitions of the "significance" of aircraft noise impacts and recommendations of land use "compatibility," however, typically lack detailed, systematic rationales. Instead, the definitions are justified by reference to decades-old policies that were adopted without benefit of modern understandings of noise-induced annoyance, by appeals to authority, and by generic citations of non-peer reviewed documents. Although regulatory policy decisions may properly take into consideration political and economic consequences, aspects of them are amenable to logical formalization. In particular, advances in understanding of community reaction to transportation noise now permit a systematic rationale for aircraft noise regulation. The current analyses show how regulatory policy positions can be derived from two parameters: (1) the minimal percentage of the population of a nominally average community to be protected from exposure to highly annoying noise; and (2) the percentage of all communities to which this degree of protection is intended to apply. Together with a reliable dosage-response relationship, these two parameters permit quantitatively justifiable definitions of significant noise impact.