Noise reduction strives to diminish the amount of noise pollution in a
given area by breaking, blocking, absorbing or isolating unwanted
infiltrating sound waves. Weakening sound wave energy levels and
suppressing echoes, reverberations, resonances and reflections are
effective manners of lessening noise pollution.
Noise pollution is becoming an increasingly serious issue in much of the modern and industrialized world as increased mechanization often leads to excessive noise produced by motors and manufacturing centers. Hearing problems, circulatory issues, difficulty sleeping and irritability are just a few symptoms of overexposure to noise. Noise reduction techniques are used in many applications to avoid these harmful. These techniques can be as simple as thick walls and acoustic curtains, or as complex as anechoic chambers. Federal regulations limit acceptable noise levels in work environments, schools, offices, airports and other public buildings. Other applications include automotive industries, construction sites, homes and even personal headsets. Active and passive noise control products are widely available. Active products are those that use electro-acoustical sound field modification or cancellation to detect and eliminate unwanted sounds. Passive products are involved more heavily in design and construction elements of a space such as acoustic ceilings, flooring, and panels.
When reducing noise in an area, several aspects of that area must be considered. Room dimensions, shape, proximity to sound wave origination and placement of doors and windows should all be considered when soundproofing a space. Likewise, it is important to determine how in depth an application will be as some involve replacing ceiling, wall and floor panels. Planning is important as strategically placed soundproofing materials and apparatus, even in a post-construction context, will significantly reduce noise pollution. Soundboards, acoustic curtains, sound barriers, acoustic baffles and other items are easily installed and can be very cost efficient. No matter the device used, materials play an integral role in noise reduction. Sound reduction indexes can help to determine the level of sound insulation provided by a given structure while noise reduction coefficients show the sound absorption levels of an acoustic material. Coefficients are measured at set frequencies allowing materials to be fitted to the specific noise conditions of a space. Common materials include rock wool, sheetrock, foam wedges, high mass vinyl, fiberglass, rubber, aluminum composite, polyethylene, mineral wool, special glass, heavy caulking, urethane open-cell foam as well as soundboards made of compressed wood and paper. Advances in computer modeling, architectural design, acoustic and material sciences allow for specified and exceptionally efficient noise reduction in any number of applications.