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The term “noise control” refers to both active and passive methods of mitigating unwanted sound in the environment. There are a number of reasons why noise control is an important consideration in both business and private settings, including personal well-being, environmental concerns, and legislative issues. However, before proper noise control solutions can be implemented, it is first necessary to determine the source and the underlying causes behind its existence. Once this has been determined, it is then possible to establish an appropriate means of circumventing further problems.
Although there are a number of common sources of noise, the two most common are aerodynamics (the motion of air) and mechanical. Noise associated with aerodynamics occurs when concentrated air movement impacts a solid object and the force of that “air strike” creates unwanted vibrations. Effective noise control in these situations often involves modifying the source of the compressed air in order to minimize its impact on the surrounding environment. One example of aerodynamic noise control in a manufacturing setting is installing pneumatic silencers into the exhaust portion of control valves to reduce the velocity and impact of the compressed air flow. In this case, the pneumatic silencers help prevent unwanted noise by effectively neutralizing the source.
On the other hand, mechanical sources of noise involve the actual collision or interaction of physical components that come into direct contact with one another. Naturally, the impact of these materials creates friction. In turn, this friction produces vibrations which then manifest in the form of noise. It’s easy to see how this would be an ongoing concern in a manufacturing environment where heavy machinery is employed. This type of equipment, which consists of many moving parts, produces excessive noise due to the friction inherent to this type of system. As with aerodynamic sources of noise, the effective resolution to this problem lies in cutting it off at its source. The challenge then becomes to reduce the ensuing vibrations and the noise associated with them.
There are four main types of effective noise control. They are sound insulation, sound absorption, vibration damping, and vibration isolation. Sound insulation involves the introduction of a noise-deadening material to the environment in order to prevent or reduce the transmission of the noise from its source to the receiver. Sound absorption is similar, except this approach employs an absorbent material designed to intercept the noise energy and transform it into heat. Vibration damping involves the mitigation of vibratory energy with solid materials (rather than air). Again, the objective is to convert that energy into heat in order to reduce its impact on the surrounding environment. Finally, vibration isolation involves the introduction of a physical barrier or break. The goal of this method of noise control is to separate the source of the unwanted vibrations from the surrounding environment. Again, the exact method of noise control employed will depend on the source and nature of the sound in question. Once this is established, the best method of noise reduction may then be determined and implemented.