ABSTRACT
The A-scale weighting network is designed to simulate the human ear's response for low pressure sounds of about 40 dB Such levels are characteristic of quiet offices and residential areas. NC values of equipment sounds may be predicted from octave band analyses by the tangent contour method. The greatest benefits in noise control are derived from quieting the source. The designer may elect to construct a wall or other acoustical barrier between the source and the exposed workers. Air-cooled motors are provided with fans attached to the rotors and usually are major sources of noise. Control valves are responsible for nearly all the noise generally blamed on piping systems. Since many aspects of noise control in power plants apply to process plant noise control, there is no need to repeat our discussion of a noise generation sources and the treatment.
