Field Of Noise Control Research Articles

A statistical theory for road traffic noise based on the composition of component response waves and its experimental confirmation

None of the existing standards, which express the needs of engineers, consider correlation properties of traffic noise. But the correlation properties of traffic noise often seem to have a fundamental importance in certain engineering fields of noise control, such as the design of barriers for sound insulation and the detection of voices in noisy out-of-doors situations. In this paper, firstly, the correlation properties in the time domain and the frequency characteristics of the sound intensity at an observation point are discussed in the general case: i.e., for arbitrary values of quantities such as the propagation characteristics of the traffic sound energy, the numbers of lanes of road and of types of vehicles, the mixture ratios of vehicle types, the average number and respective acoustic power distributions of vehicles travelling with specific velocities on each lane of the road, the lengths of the straight sections of the road and the distance from the observation point. Next, the equivalence problem of replacing the several lanes of the road by a representative single lane is also discussed in detail, as an application of the statistical method. Finally, the values obtained from the theoretical expressions for several kinds of correlation functions of lower and higher orders are compared with experimental values, as obtained by use of the digital simulation technique.

Noise control activities of the state OF California

This paper deals primarily with state activity in the field of noise control. It covers motor vehicle noise, aircraft noise, noise and land use planning, and includes a discussion of what areas for future state legislation are left uncovered by federal preemption under the Noise Control Act of 1972. With regard to motor vehicle noise, California has been enforcing existing state laws that pertain both to sellers of new vehicles and to operators of all vehicles. The enactment of the Noise Control Act raises questions as to the continued legality of the existing new vehicle laws. California's aircraft noise regulations went into effect in December 1972. As a practical matter, full enforcement must await the satisfactory performance of the monitoring systems, none of which have been fully approved. The airlines have sued the state to invalidate the regulations. The outcome may well depend on the decision of the United States Supreme Court in Burbank v. Lockheed, that court's first aircraft noise regulation case, which was scheduled to be argued in February 1973.

Aircraft noise contours and building in the USSR

Methods of calculating acceptable levels of aircraft noise within the vicinity of airports and the boundaries which it places upon the building development have been the subject of extensive investigation at the Research Institute of Building Physics in the USSR, where Dr Eng A. Klimukhin, an expert in the field of noise control and building acoustics, is deputy chief of the Acoustics Division. Recommendations now made show the areas in which residential building may be permitted, according to the noise characteristics of distinctive types of aircraft.

Instruments for noise measurement

Noise measurement is essential to all aspects of noise control. This measurement may vary from a single figure reading on a simple sound level meter to a complex analysis into narrow frequency bands, waveform investigation of peak values, directionality characteristics and the variation of the noise level with time, from which loudness level and various other factors can be calculated. Instruments for this analysis must include calibrated microphones together with some or all of the following: signal amplifier, spectrum analyser to split the noise into limited frequency bands, level indicators or level recorders, time analysis equipment. Various kinds of equipment in each category are discussed together with the application to the field of noise control.