For those living under the flight path of the busiest airport in the world

by Davinos Greeno

For those living under the flight path of the busiest airport in the world a good nights sleep has become a distant dream. A friend of mine that is sleep deprived explains why Heathrow is a Human Rights issue.The sun is out and the birds are chattering. It is blissfully quiet and I am deep in slumber. A deep droning noise jerks me awake. No, it is not my Sunday afternoon nap under the pear tree. It is 4.30 a.m. on a summer's morning and the first long haul flight of the day is about to land at Heathrow. I have to get up in two and a half hours to travel to work on a hot, sweaty tube train. Too late, though, to get back to dreamland. That jumbo has broken my sleep for good.Welcome to life under the flight path of the busiest airport in the world.In Isleworth, we can just about get used to the aeroplanes coming in every two minutes during the day because landings are rotated so that aircraft don't fly constantly over the same houses. But night flights? I don't think so.Sixteen night flights have been allowed at Heathrow between 11.30 pm and 6am since 1993. Most of the flights arrive after 4.30 am. The government is looking into the possibility of more night flights, provided aircraft use quieter engines as the older and bigger aircraft make a horrendous noise.So you can imagine how dismayed both myself, and the other 600,000 people living under Heathrow's flight paths, were to hear that the government had won its appeal against the European Court of Human Rights' ruling that night flights should be banned because we are entitled to a good night's sleep. In fact it was the European Court of Human Rights which overturned its previous decision in 2001 that "there was no overwhelming national interest for night flights at Heathrow, and therefore the residents' basic human right to sleep should not be sacrificed for the convenience of airlines".So why a change of heart by the court? Economics. According to our local paper, the Richmond and Twickenham Times, the court found that the economic benefits to the country as a whole outweighed the interests of sleepless residents. The court said that there had been no violation of Article 8 of the Human Rights Convention (HRC), the right to respect for private and family life and home. However, it did find that under Article 13 of the HRC, the residents hadn't been given the opportunity to make their case fully in the UK courts. So the fight will go on.Noise is one of the worst pollutants and can ruin your quality of life. Friends of the Earth remind us that night flights have caused many residents to suffer from constant tiredness, clinical depression, irritability, headaches and ear infections caused by wearing earplugs. It maintains that the noise caused by the night flights was substantially in excess of the World Health Organisation's guidelines for avoiding sleep disturbance at night. If you have troublesome noisy neighbours, you are protected by the Noise Act of 1996. But, guess what, it doesn't apply to aircraft noise! According to the UK Noise Association, aviation is virtually above the law.HACAN Clearskies (Heathrow Association for the Control of Aircraft Noise) is the largest voluntary organisation in Europe dedicated to campaigning on behalf of those who suffer because of aircraft flight paths. Whilst not opposed to Heathrow per se, the organisation has fought various battles over the years. It played an important part, for example, in persuading the Government to introduce runway alternation, so that residents in South West London were not continuously bombarded with noise.There is also the ongoing issue of whether there will be a third runway at Heathrow. Heathrow's proximity to London means aircraft continuously circle over the capital and come in to land over crowded urban areas. (If the 2001 Concorde crash had happened in London, and not in Paris, the plane would have come down on Ealing!)HACAN believes that a third runway would increase the possibility of a mid air collision over London. It would also mean 500 more flights a day and a plane flying over our houses every minute, not to mention bad air pollution, congested roads and public transport, and disruption of children's schooling.So let's keep battling for a decent nights sleep. We may have lost this round of the battle, but it will continue now in the UK courts. For more information, go to the HACAN website.

Aircraft noise

From Wikipedia, the free encyclopedia

Aircraft noise is defined as sound produced by any aircraft on run-up, taxiing, take off, over-flying or landing. Aircraft noise is a significant concern for approximately 100 square kilometers surrounding most major airports. Aircraft noise is the second largest (after roadway noise) source of environmental noise. While commercial aviation produces the preponderance of total aircraft noise, private aviation and military operations also play a role. It is usually measured in Decibels.
Take-off of aircraft may lead to a sound level of more than 100 decibels at the ground, with approach and landing creating lower levels. Since aircraft landing in inner-city airports are often lower than 60 meters above roof level, a sound level above 100 dBA can be realized.

1 Mechanisms of sound production
1.1 Aerodynamic noise
1.2 Engine and other mechanical noise
1.3 Noise from aircraft systems
2 Annoyance effects
3 Health effects of aircraft noise
4 Noise mitigation programs



Mechanisms of sound production

A moving aircraft including the jet engine or propeller causes compression and rarefaction of the air, producing motion of air molecules. This movement propagates through the air as pressure waves. If these pressure waves are strong enough and within the audible frequency spectrum, a sensation of hearing is produced. Different aircraft types have different noise levels and frequencies. The contributions to the total noise level originate from three main sources:
Aerodynamic noise
Engine and other mechanical noise
Noise from aircraft systems

Aerodynamic noise

Aerodynamic noise arises from the airflow around the aircraft fuselage and control surfaces. This type of noise increases with aircraft speed and also at low altitudes due to the density of the air. Jet-powered aircraft create intense noise from aerodynamics, which is typically broadband. Low flying, high speed military aircraft produce especially loud aerodynamic noise. Even though cabin sound levels may be lower in civilian commercial airliners due to added sound attenuating material, it should be noted that this exposure can lead to damage, since hearing loss is cumulative.
The shape of the nose, windshield or canopy of an aircraft can greatly affect the sound produced. Much of the noise of a propeller aircraft is of aerodynamic origin due to the flow of air around the blades. The helicopter main and tail rotors also give rise to aerodynamic noise. This type of aerodynamic noise is mostly low frequency determined by the rotor speed.

Engine and other mechanical noise

Much of the noise in propeller aircraft comes equally from the propellers and aerodynamics. Helicopter noise has a unique spectral content, essentially being aerodynamically induced noise from the main and tail rotors and mechanically induced noise from the main gearbox and various transmission chains. The mechanical sources produce narrow band high intensity peaks relating to the rotational speed and movement of the moving parts. In computer modelling terms noise from a moving aircraft can be treated as a line source.

Noise from aircraft systems

Cockpit and cabin pressurisation and conditioning systems are often a major contributor within cabins of both civilian and military aircraft. However, one of the most significant sources of cabin noise from commercial jet aircraft other than the engines is the Auxiliary Power Unit (or APU). An Auxiliary Power Unit is a relatively small self contained generator used in aircraft to start the main engines, usually with compressed air, and to provide electrical power while the aircraft is on the ground. The typical noise output of an APU is 113 decibels. This is about 27 decibels lower than that of a jet engine. Other internal aircraft systems can also contribute, such as specialised electronic equipment in some military aircraft.

Annoyance effects

Lesser intensities of noise are produced for cruising velocities, mainly due to the altitudes of operation. However, this noise often is heard in country settings which are by nature very peaceful. Thus the intrusion of this type of noise can be very intrusive even if much less in amplitude (say approximately 45 decibels). Landing aircraft descend on a three degree glide path towards an aiming point approximately 300 meters from the runway threshold. This places them at 60 meters above the ground at about 1200 meters from the aiming point or 900 meters from the start of the runway. This distance is usually outside the airport fence. Departing aircraft normally are over 150 meters above the ground before crossing the end of the runway.

A British Airways Airbus A321, on landing approach to London Heathrow Airport, showing proximity to homes.

Health effects of aircraft noise

The annoyance effects of aircraft noise are widely recognized; however, aircraft noise is also responsible for a significant amount of hearing loss as well as a contributor to a number of diseases. Only in the early 1970s did aircraft noise become a widespread topic of concern in the U.S. and federal regulations began to recognize the significance of abating these impacts in the vicinity of major commercial airports. High levels of aircraft noise that commonly exist near major commercial airports are known to increase blood pressure and contribute to hearing loss. Some research indicates that it contributes to heart diseases, immune deficiencies, neurodermatitis, asthma and other stress related diseases. Further research is being carried out to better understand these effects.
Prior research indicates clearly that hearing loss is less a product of aging than a result of exposure to transportation related noise (Rosen, 1965). Any sound louder than normal conversation can damage the delicate hair cells in the cochlea, the structure in the inner ear that converts sound waves into auditory nerve signals. Initially damage to the cochlea may be temporary, but with repeated exposure, the damage becomes permanent and tinnitus maybe develop. More recently the Centers for Disease Control and Prevention's (CDC) National Center for Environmental Health (NCEH) conducted an analysis to determine the prevalence of hearing loss among children using data collected from 1988-1994 in the Third National Health and Nutrition Examination Survey. The analysis indicates that 14.9% of U.S. children have low or high frequency hearing loss of at least 16 dB hearing level in one or both ears.
From research of the National Institutes of Health, roughly 65 million Americans are exposed to sound levels that can interfere with their function at work or disrupt sleep, and 25 million are exposed to health risk (cardiovascular, immunological, etc.) from environmental noise.

Noise mitigation programs

In the United States, since aviation noise became a major public issue in the late 1960s, governments have enacted legislative controls. Aircraft designers, manufacturers, and operators have developed quieter aircraft and more careful operating procedures. Modern high-bypass turbofan engines, for example, are quieter than the turbojets and low-bypass turbofans of the 1960s. First, FAA Aircraft Certification achieved noise reductions classified as 'Stage 3' aircraft; which has been upgraded to 'Stage 4' noise certification resulting in significantly quieter aircraft. This has resulted in lower noise exposures in spite of increased traffic growth and popularity.
In the 1980s the U.S. Congress authorized the FAA to devise technology and programs to attempt to insulate homes near airports. While this obviously does not address the exterior environment, the program has been effective for residential interiors. Some of the first airports at which the technology was applied were San Francisco International Airport and San Jose International Airport in California. The underlying technology is a computer model which simulates the impingement of aircraft noise upon building structures. One can examine variations in aircraft types, flight patterns and local meteorology. then one can evaluate the benefits of alternative building retrofit strategies such as roof upgrading, window glazing improvement, fireplace baffling, caulking construction seams and other measures. The computer model allows cost effectiveness evaluations of unlimited numbers of strategy combinations (Hogan, 1984).
Local land-use planners have considerable control over noise mitigation by reducing incompatible land uses around airports and preventing new incompatible development such as schools, homes, and high rise buildings. While the FAA and the aviation industry have made aircraft considerably quieter, local municipalities continue to zone and build homes and schools at the end of runways, such as in 2003, Readington Township, NJ which built an Elementary School at the end of Solberg Airport Runway 31. In situations such as this, only the local authorities can be responsible for this type of inadequate planning. Organizations such as AeroBlue.Org propose stronger controls to improve the integration of airports with local land-use patterns. In addition, Home Owners have a responsibility and control of where they buy a home or choose to live. Many people are not disturbed by aviation noise, or choose to live near airports for convenient travel or job-related reasons.
Another possible solution is the development of floating airports which would be situated many miles out to sea, where planes could take off and land without disturbing communities below. However, there are considerable drawbacks to this solution including significant expense, time and inconvenience to travelers in reaching an airport at sea. This includes the inability to integrate at-sea-airports with mass transit networks or proximity to related business and cargo infrastructure.

Video noise

In video and television, noise refers to the random dot pattern that is superimposed on the picture as a result of electronic noise, the 'snow' that is seen with poor (analog) television reception or on VHS tapes. Interference and static are other forms of noise, in the sense that they are unwanted, though not random, which can affect radio and television signals.

From Wikipedia, the free encyclopedia

Electronic noise

Main article: Electronic noise
Electronic noise exists in all circuits and devices as a result of thermal noise, also referred to as Johnson Noise. Semiconductor devices can also contribute flicker noise and generation-recombination noise. In any electronic circuit, there exist random variations in current or voltage caused by the random movement of the electrons carrying the current as they are jolted around by thermal energy. The lower the temperature the lower is this thermal noise. This same phenomenon limits the minimum signal level that any radio receiver can usefully respond to, because there will always be a small but significant amount of thermal noise arising in its input circuits. This is why radio telescopes, which search for very low levels of signal from stars, use front-end low-noise amplifier circuits, usually mounted on the aerial dish, and cooled with liquid nitrogen.

From Wikipedia, the free encyclopedia

Audio noise

In audio, recording, and broadcast systems audio noise refers to the residual low level sound (usually hiss and hum) that is heard in quiet periods of programme.
In audio engineering it can also refer to the unwanted residual electronic noise signal that gives rise to acoustic noise heard as 'hiss'. This signal noise is commonly measured using A-weighting or ITU-R 468 weighting
Noise is often generated deliberately and used as a test signal. The two most common types of such noise are:
white noise, which has a uniform power spectral density at all frequencies
pink noise which has a power spectral density that falls at 3dB/octave with rising frequency. The pink noise is often more useful in audio testing because it contains constant energy per octave (and hence per commonly used 1/3rd octave), rather than a preponderance of energy at high frequencies. In other words it contains energy that is distributed geometrically rather than linearly.
There are other less common kind of noise:
black noise, a term with numerous conflicting definitions, but commonly refers to silence with occasional spikes.
blue noise, contains more energy as the frequency increases.
brown noise, mimics the signal noise produced by brownian motion.
gray noise, similar to white noise, but has been filtered to make sound level appear constant at all frequency to the human ear.
green noise, an unofficial term which can mean the mid-frequencies of white noise, or the 'background noise of the world'.
orange noise, an unofficial term describing noise which has been stripped of harmonious frequencies.
purple noise, contains more energy as the frequencies increases.
red noise, an oceanograhic term which describes ambient underwater noise from distant sources. Also another name for brown noise.

From Wikipedia, the free encyclopedia

Acoustic noise

When speaking of noise in relation to sound, what is commonly meant is meaningless sound of greater than usual volume. Thus, a loud activity may be referred to as noisy. However, conversations of other people may be called noise for people not involved in any of them, and noise can be any unwanted sound such as the noise of aircraft, neighbours playing loud music, or road sounds spoiling the quiet of the countryside.
For film sound theorists and practitioners at the advent of talkies c.1928/1929, noise was non-speech sound or natural sound and for many of them noise (especially asynchronous use with image) was desired over the evils of dialogue synchronized to moving image. The director and critic René Clair writing in 1929 makes a clear distinction between film dialogue and film noise and very clearly suggests that noise can have meaning and be interpreted: "...it is possible that an interpretation of noises may have more of a future in it. Sound cartoons, using "real" noises, seem to point to interesting possibilities" ('The Art of Sound' (1929)). Alberto Cavalcanti uses noise as a synonym for natural sound ('Sound in Films' (1939)) and as late as 1960, Siegfried Kracauer was referring to noise as non-speech sound ('Dialogue and Sound' (1960)).

From Wikipedia, the free encyclopedia