Noise Mitigation or Abatement It's a Constant Concern

Architectural solutions

Main article: Architectural acoustics

Beyond the interior acoustics cited above under aircraft noise, there has been a steady trend to design quieter buildings with regard to sources within and without the structure itself.^{[citation needed]} In the case of construction of new (or remodeled) apartments, condominiums, hospitals and hotels, many states and cities have stringent building codes with requirements of acoustical analysis, in order to protect building occupants. With regard to exterior noise, the codes usually require measurement of the exterior acoustic environment in order to determine the performance standard required for exterior building skin design. The architect can work with the acoustical scientist to arrive at the best cost-effective means of creating a quiet interior (normally 45 dBA). The most important elements of design of the building skin are usually: glazing (glass thickness, double pane design etc.), roof material, caulking standards, chimney baffles, exterior door design, mail slots, attic ventilation ports and mounting of through the wall air conditioners.
Regarding sound generated inside the building, there are two principal types of transmission. 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. Human activities might include voice, amplified sound systems or animal noise. Mechanical systems are elevator systems, boilers, refrigeration or air conditioning systems, generators and trash compactors. Since many of these sounds are inherently loud, the principal design element is to require the wall or ceiling assembly to meet certain performance standards^[7] (typically Sound transmission class of 50), which allows considerable attenuation of the sound level reaching occupants.
The second type of interior sound is called Impact Insulation Class (IIC) transmission. This effect arises not from airborne transmission, but rather from transmission of sound through the building itself. The most common perception of IIC noise is from footfall of occupants in living spaces above. 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.
Both of the above transmission effects may emanate either from building occupants or from building mechanical systems such as elevators, plumbing systems or heating, ventilating and air conditioning units. In some cases it is merely necessary to specify the best available quieting technology in selecting such building hardware. In other cases shock mounting of systems to control vibration may be in order. 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.
Designing special purpose rooms has more exotic challenges, since these rooms may have requirements for unusual features such as concert performance, sound studio recording, lecture halls. In these cases reverberation and reflection must be analyzed in order to not only quiet the rooms but prevent echo effects from occurring. In these situations special sound baffles and sound absorptive lining materials may be specified to dampen unwanted effects.

Noise Polllution Another Man-made Problem and Only Getting Worse

noise pollution

noise pollution, human-created noise harmful to health or welfare. Transportation vehicles are the worst offenders, with aircraft, railroad stock, trucks, buses, automobiles, and motorcycles all producing excessive noise. Construction equipment, e.g., jackhammers and bulldozers, also produce substantial noise pollution.

Noise intensity is measured in decibel units. The decibel scale is logarithmic; each 10-decibel increase represents a tenfold increase in noise intensity. Human perception of loudness also conforms to a logarithmic scale; a 10-decibel increase is perceived as roughly a doubling of loudness. Thus, 30 decibels is 10 times more intense than 20 decibels and sounds twice as loud; 40 decibels is 100 times more intense than 20 and sounds 4 times as loud; 80 decibels is 1 million times more intense than 20 and sounds 64 times as loud. Distance diminishes the effective decibel level reaching the ear. Thus, moderate auto traffic at a distance of 100 ft (30 m) rates about 50 decibels. To a driver with a car window open or a pedestrian on the sidewalk, the same traffic rates about 70 decibels; that is, it sounds 4 times louder. At a distance of 2,000 ft (600 m), the noise of a jet takeoff reaches about 110 decibels—approximately the same as an automobile horn only 3 ft (1 m) away.

Subjected to 45 decibels of noise, the average person cannot sleep. At 120 decibels the ear registers pain, but hearing damage begins at a much lower level, about 85 decibels. The duration of the exposure is also important. There is evidence that among young Americans hearing sensitivity is decreasing year by year because of exposure to noise, including excessively amplified music. Apart from hearing loss, such noise can cause lack of sleep, irritability, heartburn, indigestion, ulcers, high blood pressure, and possibly heart disease. One burst of noise, as from a passing truck, is known to alter endocrine, neurological, and cardiovascular functions in many individuals; prolonged or frequent exposure to such noise tends to make the physiological disturbances chronic. In addition, noise-induced stress creates severe tension in daily living and contributes to mental illness.

Noise is recognized as a controllable pollutant that can yield to abatement technology. In the United States the Noise Control Act of 1972 empowered the Environmental Protection Agency to determine the limits of noise required to protect public health and welfare; to set noise emission standards for major sources of noise in the environment, including transportation equipment and facilities, construction equipment, and electrical machinery; and to recommend regulations for controlling aircraft noise and sonic booms. Also in the 1970s, the Occupational Safety and Health Administration began to try to reduce workplace noise. Funding for these efforts and similar local efforts was severely cut in the early 1980s, and enforcement became negligible.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2007, Columbia University Press. All rights reserved.

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A Brief Histroy of Resilient Channel

History of Resilient Channel:

Resilient Channel was originally brought to the mass market decades ago by USG (United States Gypsum). The product was trademarked as RC-1, and tested extensively at Riverbank Acoustic Laboratories. Today many installers, architects and material retailers refer to any channel with one “leg” as RC-1. It’s important to note that USG hasn’t dealt with the original resilient channel design for years and years. Since then, many manufacturers have made a “resilient channel” and informally referred to previous USG test data for acoustic performance. This is entirely misleading and quite unfortunate. Resilient channel available today has many profiles, mil thicknesses and performance characteristics, so it really not possible to simply predict how any given piece of “resilient channel” will perform. Additionally any 1 or 2 legged resilient channel is not specified by the Steel Stud Manufacturers Association (SSMA). So there are no standards for its construction or use.

How Acoustic Barriers Reduce Sound

Anyone who's ever shared a wall with someone else has probably wondered if the walls were intentionally thin, or the neighbors intentionally loud. Often the assumption is that the walls between dwellings simply need to be thicker to muffle sound. The fact is that the design of the wall, not the size, can be a contributing factor in transmitting sound from one side to the other.

Consider how walls are constructed in most multi-family housing units. Basically, they are made of gypsum board firmly attached to both sides of a wood frame. When sound waves hit one side of the wall it causes the gypsum board on that side to vibrate. Since the gypsum board is rigidly connected to the frame, the vibration is transmitted right through the framing to the gypsum board on the other side. Those same vibrations travelling through the wall frame can also send sound throughout adjacent floors and ceilings. Noises will radiate through the structure because there's almost nothing there to cushion or absorb the sound waves.

In order to significantly dampen those approaching sound waves, United Plastics Corporation’s dB-3 Pro can be installed between one of the gypsum walls and the frame. The United Plastics Corporation dB-3 Pro, which is made of 100% post-industrial materials  acts as a shock absorber in this system, muffling vibrations coming from either side of the wall. United Plastics Corporation’s dB-3 Pro is an improvement over the resilient channel system’s that are routinely used to improve the sound ratings for walls and are especially effective in floor/ceiling constructions.

Resilient channels typically add 3 to 5 Sound Transmission Class (STC) points to an otherwise identical wall or ceiling, whereas United Plastics Corporation’s dB-3 Pro up’s the ante by adding between 3-5 Sound Transmissions Class (STC) points per layer. This can most often is more than enough to meet the STC and Impact Insulation Class (IIC) ratings required by the project design goals or local codes. In California, the building code specifies minimum lab tested ratings of STC 50 and IIC 50 for partitions in multi-family dwellings.

In fact, the IIC 50 rating required by the building code is easily achieve using the dB-3 Pro wall material when hung in the ceiling in a multi-family project. Unless the floors are completely carpeted (which is rare for kitchens and bathrooms), it is very difficult to achieve IIC 50 ratings without using resilient channels and batt insulation in the floor-ceiling construction

Just what is the difference between Structure-borne and Air-borne noise?

	The noise given off by a particular source can usually be categorised into one of the following forms: Structure-borne noiseThis is the sound generated from a vibrating source or impact event. The acoustic energy created by these vibrations is transmitted into the structure of a building (e.g. floors, walls, pipe-work etc,) or into mechanical elements (e.g. metal frames, panel work, supports etc.) This energy travels through solid structures and is released as air-borne noise at different locations within the building or mechanical system. Air-borne noise This is the sound that travels through the air and into the surrounding environment. In closed environments such as rooms and enclosures, air-borne sound may reverberate and increase the levels of noise both in and outside the contained space. Most forms of noise will contain contributions from both air-borne and structure-borne sound. Although measures can be taken to limit structure-borne components, such as by isolation and damping, air-borne sound can be treated with the use of absorbing materials. ArmaSound RD has an extremely high absorption performance per unit thickness, offering a solution for the most demanding applications.
	By way of example, someone who is hammering a nail into a wall (See diagram) will create structural noise, causing vibration of the surrounding structure. However, they will create a significant amount of air-borne noise, which will be clearly heard in the room where the action is taking place. As the noise travels, it may also change forms. I.e. Structure-borne noise may eventually cause sympathetic vibrations in other structures and release airborne sound. In this example, the structure borne components of the noise may travel towards the light fitting that’s in the same room causing it to shake and release audible clatter. Airborne noise may also change into structure-borne and back to air-borne. This process is often called ‘transmission’ of sound energy. Once again, in the example above, the air-borne components of the noise may travel into the far wall, and then out through the other side and into an adjoining room.

Noise - A Universal Complaint

Noise - A Universal Complaint

According to a recent Daily News poll, most New Yorkers cite NOISE as the most annoying feature of urban life(1). Furthermore, when the NYC Police Department instituted its quality of life telephone hotline in August, 1996, 43% of complaints received related to noise(2).

The noise that annoys New Yorkers comes in many forms from many places. Shrieking subways(3), thudding pile drivers(4), roaring boilers(5), noisy neighbors(6), raucous restaurants(7). Community meetings throughout the City regularly address the failure or refusal of City agencies to effectively respond to noise complaints.

Excessive Noise is Unhealthy

Excessive noise is hazardous to our physical and mental health(8). The body reacts to unwelcome noise of any intensity indirectly as it does to other intrusive stressful stimuli: elevated blood pressure, excessive secretion of hormones, changes in the rhythm of the heart. There is a growing body of literature that suggests that these physiological responses may lead to actual bodily damage in adults and in children(9). In addition, the frustration of not being able to limit distracting noise compounds the body's physiological responses. In some cases, noise drives people to commit homicide or suicide

If this is a sign of the times then Sound Control best be on everyone's mind

Reprinted from Associated Press Tuesday, December 20, 2011

Rise in home building suggests industry turnaround

Dec. 20, 2011, 1:46 p.m. EST

AP

WASHINGTON (AP) — A surge in apartment construction gave home builders more work in November. And permits, a gauge of future construction, rose largely because of a jump in apartment permits.
Some analysts say the gains, though coming off extremely low levels, suggest the depressed housing industry may have reached a turning point.
Economists now say 2011 will be the first year since the Great Recession began in 2007 that home construction will have helped the economy grow. Before this year, the industry endured two of the worst years ever.
"Homebuilding is through the worst and is now steadily improving," said Paul Diggle, a property economist at Capital Economics.
Builders broke ground on a seasonally adjusted annual rate of 685,000 homes in November, a 9.3 percent jump from October, the government said Tuesday. It's the highest level since April 2010.
Still, the rate is far below the 1.2 million homes that economists say would be built each year in a healthy housing market.
Construction of single-family homes rose 2.3 percent in November to a seasonally adjusted annual rate of 447,000. Apartment construction jumped 32 percent to a rate of 238,000 units. Single-family homes account for about 70 percent of homebuilding.
For the year, work is expected to have begun on 430,000 single-family homes and 185,000 apartments. Those figures remain far below the roughly 840,000 single-family homes and 360,000 apartments that would be started in a healthy economy.
Tuesday's home construction data, along with encouraging economic news out of Germany and Spain, helped fuel a huge rally on Wall Street. The Dow Jones industrial average jumped more than 300 points, or 2.7 percent, by mid-afternoon.
Patrick Newport and Michelle Valverde, U.S. economists at IHS Global Insight, said the better-than-expected figures show that the housing industry is "finally getting off the mat."
"It'll keep getting better through next year," said Jared Franz, an associate economist at T. Rowe Price.
Last year, builders began work on roughly 587,000 homes. That barely surpassed the 554,000 homes started in 2009, the worst year ever.
Though new homes represent just 20 percent of the overall home market, they have an outsize impact on the economy. Each home built creates an average of three jobs for a year and generates about $90,000 in taxes, according to the National Association of Home Builders.
Renting has become a preferred option for many Americans who lost their jobs during the recession and were forced to leave their houses. The surge in apartments has provided a lift to the beleaguered housing market but has not been enough to completely offset the loss of single-family homes.
Permits rose 5.7 percent last month to a seasonally adjusted annual rate of 681,000, boosted by a 16 percent jump in permits for apartment buildings, to 246,000.
Builders typically begin construction on single-family homes six months after getting a permit. With apartment projects, the lag time can be up to a year.
Over the past year, permits for apartment buildings with five or more units have surged more than 80 percent. Permits for single-family homes have risen much less: just 3.6 percent.
Demand for new homes is weak. Record-low mortgage rates and plunging home prices have done little to help.
The chief problem: Builders are struggling to compete with deeply discounted foreclosures and short sales. Short sales occur when lenders allow homes to be sold for less than what's owed on the mortgage. Few homes are selling.
After previous recessions, housing accounted for at least 15 percent of U.S. economic growth. Since the recession officially ended in June 2009, it has contributed just 4 percent.
In October, sales of new homes rose slightly, largely because builders cut their prices in the face of weak demand. Sales hit a six-month low in August. And this year is shaping up to be the worst since the government began keeping records a half-century ago.
Another reason sales have fallen is that previously occupied homes have become a better deal than new homes. The median price of a new home is about 30 percent higher than the median price for a re-sale. That's nearly twice the markup typical in a healthy housing market.
The homebuilders' trade group said this week that its survey of industry sentiment rose in December to 21, the highest level since May 2010. Still, any reading below 50 indicates negative sentiment about the housing market. The index hasn't reached 50 since April 2006, the peak of the housing boom.