Sample size implications for calculations of community tolerance level values from social surveys of noise-induced annoyance

The relationship between noise exposure and the prevalence of annoyance of transportation noise in a community is commonly characterized by a so-called dose-response curve, also referred to as exposure-response curves. Such curves are generally estimated by meta-analyses of social survey findings. Large numbers of survey respondents are generally assumed to be associated with exposure-response relationships of high accuracy and precision. The community tolerance level (CTL) approach [Fidell, Mestre, Schomer, Berry, Gjestland, Vallet, and Reid (2011). J. Acoust. Soc. Am 130, 791-806] to analysis of noise-induced annoyance in communities assumes (1) that the prevalence of a consequential degree of annoyance in communities grows as does the duration-adjusted loudness of noise exposure, and (2) that this rate-of-growth function is constant for all transportation noise sources. Because CTL analysis assumes a growth function with a single parameter the entire relationship between noise exposure and prevalence of high annoyance can be described by a single quantity-a CTL value. A re-analysis of the results of about 100 social surveys shows that a sample of about 300 respondents yields results with useful precision limits for regulatory purposes.