Noise control

Many of these techniques rely upon material science applications of constructing sound baffles or using sound-absorbing liners for interior spaces.

[3][4] MSHA requires that administrative and/or engineering controls must be implemented in the workplace when miners are exposed to levels above 90 dBA TWA.

[7][4] The European Parliament and Council directive require noise levels to be reduced or eliminated using administrative and engineering controls.

Speed control is effective since the lowest sound emissions arise from vehicles moving smoothly at 30 to 60 kilometers per hour.

Selection of road surface pavement can make a difference of a factor of two in sound levels, for the speed regime above 30 kilometers per hour.

They are one of the most effective actions taken in retrofitting existing roadways and commonly can reduce adjacent land-use sound levels by up to ten decibels.

A computer model is required to design the barrier since terrain, micrometeorology and other locale-specific factors make the endeavor a very complex undertaking.

For example, a roadway in cut or strong prevailing winds can produce a setting where atmospheric sound propagation is unfavorable to any noise barrier.

Because of its velocity and volume, jet turbine engine exhaust noise defies reduction by any simple means.

The most promising forms of aircraft noise abatement are through land planning, flight operations restrictions and residential soundproofing.

Variations in aircraft types, flight patterns and local meteorology can be analyzed along with benefits of alternative building retrofit strategies such as roof upgrading, window glazing improvement, fireplace baffling, caulking construction seams and other measures.

), perforated metal (used internally or externally),[20] roof material, caulking standards, chimney baffles, exterior door design, mail slots, attic ventilation ports, and mounting of through-the-wall air conditioners.

Firstly, airborne sound travels through walls or floor and ceiling assemblies and can emanate from either human activities in adjacent living spaces or from mechanical noise within the building systems.

This type of noise is more difficult to abate, but consideration must be given to isolating the floor assembly above or hanging the lower ceiling on resilient channel.

In the case of plumbing systems, there are specific protocols developed, especially for water supply lines, to create isolation clamping of pipes within building walls.

In the case of central air systems, it is important to baffle any ducts that could transmit sound between different building areas.

Acoustical wall and ceiling panels are a common commercial and residential solution for noise control in already-constructed buildings.

While this circumstance is the most dramatic, there are many other work environments where sound levels may lie in the range of 70 to 75 decibels, entirely composed of office equipment, music, public address systems, and even exterior noise intrusion.

Either type of environment may result in noise health effects if the sound intensity and exposure time is too great.

In certain cases the machinery itself can be re-designed to operate in a manner less prone to produce grating, grinding, frictional, or other motions that induce sound emissions.

In recent years, Buy Quiet programs and initiatives have arisen in an effort to combat occupational noise exposures.

One source of annoying, if not loud, sound level emissions are lighting fixtures (notably older fluorescent globes).

[24] Acoustically absorbent materials such as fiberglass duct liner, wood fiber panels and recycled denim jeans serve as artwork-bearing canvasses in environments in which aesthetics are important.

A large secondary market of homemade and home use acoustic panels, bass trap, and similar constructed products has developed resulting from this demand, with many small companies and individuals wrapping industrial and commercial-grade insulations in fabric for use in home recording studios, theatre rooms, and music practice spaces.

Because low-income neighborhoods are often at greater risk of noise pollution, the establishment of such zoning codes is often an environmental justice issue.

[25] Mixed-use areas present especially difficult conflicts that require special attention to the need to protect people from the harmful effects of noise pollution.