Noise control techniques

In all hearing protection activites, the first consideration must be to eliminate the source of noise and hence protect all the workforce. However, it is not always possible to eliminate noise emissions completely so action must be taken to reduce emissions as far as possible. This should be done logically following a thought-out strategy. 

Two approaches to a hearing protection strategy (each with a listing in order of priority) are  

Specialized knowledge of the material to be used and its most effective method of application is required to ensure that noise suppression and control techniques are effective. It is advisable to call in specialists. 

A last resort, after all other techniques have proved ineffective, is to provide personal hearing protection which  

It may be prudent to offer employees a choice of type of personal hearing protection, subject always to the chosen type providing adequate level of protection, i.e. a suitable level of attenuation and being compatible with other protective equipment that has to be worn. 

X- must be kept scrupulously clean or can introduce dirt in ear canal and cause inflammation preventing further use of device 

Having identified the nature and magnitude of any noise problem, the essential elements of a noise control programme are provided. Where a problem is evident, there are three orders of priority for a solution  

1 Engineer tiie problem out by bu5ung low noise equipment, altering the process or changing operating procedures. 

2 Apply conventional metiiods of noise control such as enclosures or silencers. 

3 Where neitiier of the above approaches can be used, the last resort of providing personal protection should be considered. 

Altiiough tile control of noise at source is the most obvious solution, the feasibility of tiiis method is often limited by machine design, process or operating methods. While immediate benefits can be obtained, this method should be regarded as a long-term solution. 

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Outlines the basic noise control techniques isolation, insulation, absorption, damping, silencing. 

Barnes, J.R. 1987. Electronic System Design Interference and Noise Control Techniques. Prentice-Hall, Englewood Cliffs, NJ. 

Is the necessary Information, Instruction and training on noise control techniques given to site workers ... 

Power Supply Cookbook, Second Edition has been updated with the latest advances in the field of efficient power conversion. Efficiencies of between 80 to 95 percent are now possible using these new techniques. The major losses within the switching power supply and the modern techniques to reduce them are discussed at length. These include synchronous rectification, lossless snubbers, and active clamps. The information on methods of control, noise control, and optimum printed circuit board layout has also been updated. 

The effect is normally one of degree. The measurement of a corrosion potential does not influence the surface condition. Electrochemical noise and impedance measurements carried out at the corrosion potential also have little effect as does a polarization resistance measurement if the perturbation is small, although rest potential drift may be a problem if potential control techniques are used. Techruques involving large potential differences will in general modify a surface significantly. 

There are a variety of control techniques, documented in the literature, to reduce overall worker exposure to noise. Such controls reduce the amount of sound energy released by the noise source, divert the flow of sound energy away from the receiver, or protect the receiver from the sound energy reaching him or her. For example, types of noise controls include proper maintenance of equipment, revised operating procedures, equipment replacements, acoustic shields and barriers, equipment redesign, enclosures, administrative controls, and personal protective equipment. 

The majority of noise control work undertaken by the safety adviser will involve the measurement and possibly the analysis of noise. It is therefore important that the use and the limitations of sound pressure level measurements and sound level meters are understood. Errors in measurement technique or interpretation could lead to costly mistakes or over-specifying in remedial measures. 

The treatment of any noise source or combination of sources may use any of the control techniques individually or in combination. The selection of suitable measures will depend on ... 

Noise control is an important aspect of computer and electronic systems. The process of noise control through proper grounding techniques is more correctly called referencing. IEEE Std 1100 [6] covers the referencing and grounding of sensitive electronics equipment. 

Active Damping and Reduction of Structural Oscillations. Under this heading, the research groups develop fundamental concepts of optimized positioning and integrating adaptronic components (actuators, sensors) in machine tool structures. Research focuses on approaches and implementations that will reduce structure-born noise by means of control techniques. 

Engineering Controls Measures taken to prevent or minimize hazard exposure through the application of controls such as improved ventilation, noise reduction techniques, chemical substitution, equipment and facility modifications, etc. 

In addition to reduced time exposure of employees to the noise source, there is a simple hierarchy of control techniques ... 

Revell, J. D., Balena, F. J. and Koval, L. R., Analytical Study of Interior Noise Control by Fuselage Design Techniques on High-Speed, Propeller-Driven Aircraft, NASA CR-159200, 1978. 

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