A Building Code for Exterior-Noise Isolation

Abstract

A building code has been formulated to describe various constructions to cause a specified noise-level reduction in a given noise zone in the city of San Diego. Noise-level reduction means reduction in average A-weighted sound level from outside to inside a building. The average noise level is that called the annual community noise equivalent level according to now effective “Noise Regulations for California Airports”; this average is a mean-square A-weighted sound-pressure level obtained with the noise levels existing between 7 p.m. and 10 p.m. increased by five decibels and the noise levels between 10 p.m. and 7 a.m. increased by 10 decibels. A noise zone is an area of the city bounded by contours of annual community noise equivalent level, at intervals of five decibels. Noise-level reduction is required by the code such as to limit to 45 decibels the average noise level inside a residential building due to outside noise of whatever source. For calculating noise-level reduction from room size and construction materials, a noise spectrum is specified that is typical of aircraft and other noise in one of the noise zones. If needed to verify compliance with the building code, a simple test of noise-level reduction is provided that can be performed with noise generally prevailing outside the building.