Community Noise Measurements Research Articles

Omnidirectional high-frequency sound level meters.

Measurement of community noise and factory noise calls for microphones that are omnidirectional. High-frequency response is also essential because A-weighted measurements, used in this work, emphasize the frequencies from 500 Hz to 10 kHz. Present standards for sound level meters guarantee neither omnidirectionality nor high-frequency response. So, accurate measures of noise environments depend on the proper choice of microphones and adaptors.

Community Noise Measurements in Los Angeles, Detroit, and Boston

Quantitative descriptors of the noise environment have been obtained for 20 urban areas in Los Angeles, Detroit, and Boston. Measurements involved the acquisition of a 10-min noise sample once each hour for a complete 24-h day, and the subsequent analysis of each noise sample to obtain a statistical distribution of the A-weighted noise levels and the number and frequency of occurrence of discrete noise intrusions. We present the time patterns of various community noise descriptors, such as the 50% level, the energy mean, the Noise Pollution Level (NPL), and the Traffic Noise Index (TNI), for several of the areas sampled. These noise measures show considerable spread in average daytime and nighttime levels. When classified in three groups according to gross differences in exposure to motor vehicle traffic, distinct differences in daytime and nighttime noise patterns and in sources of discrete noise intrusions are apparent. The several noise measures (including the 1, 10, 50, and 90% A-levels, TNI and NPL), generally show high correlation among each other, with the exception of the TNI when it is calculated on other than a 24-h basis.

Measurement of Community Noise

A draft proposal for a uniform method of measuring community noise, developed by the USASI S3-50 Working Group, presents a method for obtaining and analyzing community noise data to serve as a basis for noise-control codes and engineering-design goals. The various procedures and requirements are discussed along with the reasoning on which the proposed standard is based.

Measurement and Evaluation of Outdoor Community Noise

This new group it attempting to translate the recommendations of the other groups concerned with measuring output of noise sources and those concerned with rating human reactions to noise into some practical limits or guidelines to facilitate application of current knowledge to control of outdoor community noise. First, a standard procedure for measuring outdoor community noise that will assure consistent results by independent investigators must be developed. The procedure must evaluate the ambient noise of unidentifiable sources upon which the noise of identifiable sources may be superimposed. Another procedure is needed for measuring the noise output of individual sources that contribute to community noise such as mowers, power boats, snowmobiles, etc., and a general procedure usable for many types of sources will be drafted. As the work of this and other groups progresses, plans call for developing (1) limits for noisy equipment, (2) limits for new products to be met by the innovator, (3) guidelines for land use management and planning, (4) community noise measurement methods and limits, and (5) recommended methods of enforcement.