Highlights of the Guidelines for Environmental Impact Statements with Respect to Noise

At the request of the U.S. Evnironmental Protection Agency (EPA), the National Academy of Sciences-National Research Council Committee on Hearing, Bioacoustics, and Biomechanics (CHABA) has developed and recently published guidelines for preparing environmental impact statements (EIS) on noise. The document contains guidance on the assessment of general audible noise and criteria to describe the environmental impact of vibration, infrasound, and high-energy type impulses. The yearly average day-night sound level outdoors is the recommended measure for the general audible noise environment. One of the key concepts introduced is the single number quantification of the overall noise impact. This single number is approximately proportional to the total number of persons that would report to be highly annoyed due to the residential yearly day-night average sound levels. The implications of such a single number descriptor, as well as other key features of the guidelines, are discussed.