The Cacophony Of Airports: A Noise Symphony

Airports are noisy places. The noise produced by aircraft in flight has been associated with several negative stress-mediated health effects, from sleep disorders to cardiovascular disorders. Aircraft noise is produced by three main sources: engine and other mechanical noise, aerodynamic noise, and noise from aircraft systems. Engine noise is particularly noticeable when fan blades reach supersonic speeds, and it can exceed 140 decibels during takeoff. Aerodynamic noise is caused by the airflow around the surfaces of the aircraft, especially when flying low and at high speeds. Aircraft systems such as cockpit and cabin pressurization, conditioning systems, and auxiliary power units also contribute to the overall noise level.

The impact of aircraft noise on those living near airports can be significant. A German study found that a daytime average sound pressure level of 60 decibels increased coronary heart disease by 61% in men and 80% in women. Night-time noise is particularly disruptive, with one study showing that a night-time average sound pressure level of 55 decibels increased the risk of heart attacks by 66% in men and 139% in women.

In response to the adverse effects of aircraft noise, governments have enacted extensive controls on aircraft designers, manufacturers, and operators, resulting in improved procedures and cuts in noise pollution. Quieter aircraft, better operating procedures, and noise insulation in homes near airports are some of the measures that have been implemented.

The different sources of airport noise

Airports are notoriously noisy places, and this noise can be attributed to several sources. Firstly, we have engine and mechanical noise, which is most noticeable when the fan blades of a jet engine reach supersonic speeds, creating a "buzzsaw" effect. This type of noise also occurs in propeller aircraft and helicopters, and it is particularly intense in low-flying, high-speed military aircraft.

Secondly, there is aerodynamic noise, which is caused by the airflow around the surfaces of the aircraft. This type of noise increases when an aircraft is flying at low altitudes and high speeds. The shape of the aircraft's nose, windshield, or canopy can also affect the sound produced by aerodynamic noise.

Thirdly, noise can come from various aircraft systems such as the cockpit, cabin pressurization, conditioning systems, and auxiliary power units (APUs). APUs are particularly significant sources of noise in commercial jet aircraft.

In addition to these sources, the movement of aircraft on the ground, such as during taxiing or run-up, can also generate noise. For propeller aircraft, taxiing and run-up are often equally as noisy as the propellers themselves.

While airborne, the main sources of noise are the engines and the high-speed turbulence over the fuselage. Aircraft engines can produce noise levels exceeding 140 decibels during takeoff, and even during cruise, noise levels inside the cabin can be around 78 decibels.

How airport noise affects people's health

Airport noise can affect human health and well-being in a variety of ways. Here are some of the most common adverse health effects associated with aviation noise:

Annoyance

The most widespread and well-documented subjective response to noise is annoyance, which can be defined as a feeling of resentment, displeasure, discomfort, dissatisfaction, or offence that occurs when noise interferes with thoughts, feelings, or activities. The annoyance of populations exposed to environmental noise varies not only with the sound itself (such as how loud it is or its pitch) but also with social, psychological, or economic factors.

Cognitive Impairment

There has been a lot of research into the effect of aircraft noise on cognitive performance in school children due to the interruptive nature of high levels of aircraft noise. Research has suggested effects on reading comprehension and memory. Cognitive performance affects attention, perception, mood, learning, and memory.

Sleep Disturbance

Aircraft noise is intermittent in nature, and exposure to it during the night may result in sleep disturbance. Noise-induced sleep disturbance refers to awakenings, changes to sleep structure such as changes to sleep stages, arousals in heart rate, and body movements. People may or may not be aware of such disturbances, but they can result in next-day fatigue.

Cardiovascular Disease

Aircraft noise at high levels can be considered a stressor on the body, and research has found an association between high levels of aircraft noise and an increased risk of developing cardiovascular disease (CVD). It is thought that this occurs due to the way such stressors interact with the body, and the fact that the cardiovascular response to noise does not decrease, even though individuals may no longer consciously notice or react to the noise.

Other Health Issues

According to studies, people exposed to noise exceeding 60 dB a day have a 30% higher risk of dying from heart attacks than those exposed to only 45 dB a day. The more aircraft noise one is exposed to and the longer the exposure, the higher the risk of health issues. Other health issues caused by aircraft noise include reduced learning capacity in children, psychological effects such as irritation, and effects on pregnancy, with noise able to affect the weight of the child at birth.

How airport noise affects children's learning

Airport noise can be described as the "constant roar from jet aircraft", and it can have a detrimental impact on the health and well-being of children. Here is an expanded discussion on how airport noise affects children's learning:

Impact on Learning

Chronic exposure to aircraft noise has been linked to adverse effects on children's learning and cognitive development. Several studies have found that children exposed to aircraft noise at school or at home tend to have poorer reading and memory skills. The RANCH study, which examined 2844 children aged 9-10 years old from schools near London Heathrow, Amsterdam Schiphol, and Madrid Barajas airports, found that exposure to aircraft noise was associated with poorer reading comprehension and recognition memory, even after accounting for social position and road traffic noise. A 5 dB increase in aircraft noise exposure was linked to a 1-2 month delay in reading age.

Interventions to Reduce Noise Exposure

Interventions to reduce aircraft noise exposure at schools have been shown to improve children's learning outcomes. For example, the Munich Airport study found that high noise exposure before the airport relocation was associated with poorer long-term memory and reading comprehension in children. However, two years after the airport closed, these cognitive impairments were no longer present, suggesting that the negative effects of aircraft noise on cognitive performance may be reversible. Similarly, a study of 6000 schools near the top 46 US airports found significant associations between aircraft noise and standardized tests in mathematics and reading. When sound insulation was installed in a subset of 119 schools, the negative impact of aircraft noise on children's learning disappeared.

Mechanisms Linking Noise Exposure and Learning

Aircraft noise may directly impact the development of cognitive skills, but there are also several proposed pathways and mechanisms for the effects. These include communication difficulties, teacher and student frustration, reduced morale, impaired attention, increased arousal, and sleep disturbances from home exposure, which can carry over to the next day and impact task performance. Noise can also cause annoyance, particularly when it interferes with an individual's activities or communication. In some cases, annoyance responses may lead to physiological and psychological stress responses, which could contribute to poorer learning outcomes.

Guidelines for Children's Noise Exposure at School

The World Health Organization (WHO) and the American National Standards Institute (ANSI) have developed guidelines to minimize the impact of noise on children's learning. The WHO recommends that the background sound pressure level in school classrooms should not exceed 35 dB L Aeq during teaching sessions to ensure adequate speech intelligibility and reduce disturbances. Additionally, the outdoor playgrounds of schools should not exceed 55 dB L Aeq during recess to prevent annoyance. The ANSI standard suggests a maximum internal background noise level of 35 dB L Aeq for unoccupied classrooms.

How airport noise affects sleep

Airport noise can be more than just a background nuisance—it can have a significant impact on the sleep of nearby residents. Aircraft noise has been identified as a major environmental noise problem, and with the rapid growth of air traffic, it is becoming an increasingly pressing issue.

Research has shown that exposure to aircraft noise can lead to sleep disturbances, with a higher prevalence of insomnia and daytime hypersomnia among residents living near airports. This can have knock-on effects on overall health and well-being, as sleep deprivation is linked to various health problems such as obesity, hypertension, diabetes, and cardiovascular disease.

One study found that a person experiencing noise from overhead as low as 45 decibels was less likely to sleep for seven or more hours a night, the recommended amount for adults. This study, which was conducted around 90 US airports, also revealed that aircraft noise can affect sleep patterns, with evening and nighttime flights particularly disruptive to sleep.

The impact of airport noise on sleep is not limited to those living in close proximity to airports. A national study in the US found that airport noise exposure was associated with self-reported sleep insufficiency, even when controlling for individual sociodemographic characteristics and socioeconomic status.

The effects of airport noise on sleep are not limited to the immediate vicinity of the airport. A national study in the US found that airport noise exposure was associated with self-reported sleep insufficiency, even when controlling for individual sociodemographic characteristics and socioeconomic status. This suggests that the impact of airport noise on sleep is not limited to those living in close proximity to airports but can extend to a wider area.

The relationship between airport noise and sleep is a complex one, and further research is needed to fully understand the causal mechanisms. However, the existing evidence suggests that airport noise can have a significant impact on the sleep of nearby residents, with potential consequences for their overall health and well-being.

How to reduce airport noise

Airport noise can be a nuisance for those living nearby, and it can be challenging to soundproof an already-built home. However, there are several ways to reduce airport noise and create a quieter environment. Here are some detailed instructions on how to minimise the impact of airport noise:

Soundproofing Your Home

• Windows: Windows often allow a lot of outside noise to enter your home due to the material used and the presence of gaps. Soundproofing your windows can significantly reduce aircraft noise. This can be achieved by hanging sound-blocking curtains, which are made from materials with sound-absorbing properties and are denser than regular curtains. Alternatively, you can seal the gaps in your windows using soundproof weather strips, or create your own window plugs by making noise-reducing window inserts that can be easily removed. If you have the budget, you can also invest in acoustically treated windows, which are soundproofed.
• Ceiling: As aircraft noise may penetrate through the ceiling, adding an extra layer of drywall using green glue noise-proofing adhesive can effectively dampen the sound. Another option is to attach acoustic foam panels to the ceiling, which will help lower the noise levels while also being aesthetically pleasing.
• Doors: Gaps between the door and the door frame can allow outside noise to enter your home. You can soundproof your door by sealing these gaps with a soundproof door weather stripping kit. Additionally, using thick blankets, such as moving blankets, to cover the door can also help block out noise.
• Walls: Walls are a significant source of low-frequency sounds, and bass traps can be used to combat this issue. Place one bass trap in each corner of the wall to help dampen external sounds. Alternatively, you can build a room within a room by using green glue and drywall to create an additional layer of soundproofing.
• White Noise: Instead of focusing on blocking out aircraft noise, you can use a white noise machine to play relaxing and soothing sounds. This can help you feel more relaxed and at ease in your environment.
• Ear Protection: When sleeping, you can use ear muffs, earplugs, or noise-cancelling headphones to block out airport noise.

Airport Noise Reduction Strategies

In addition to soundproofing your home, there are also strategies that can be implemented at the airport level to reduce noise:

• Aircraft Technology: Improving aircraft engine and airframe technology has been an ongoing focus to reduce noise, fuel burn, and emissions. Modern jet aircraft are significantly quieter than older models, and each new generation has a lower noise footprint.
• Air Traffic Management: Controlling the flight paths of planes during take-off and landing can minimise noise pollution. Airports can work with air traffic management to map out flight tracks that avoid densely populated areas, ensuring planes travel over seas, lakes, or less noise-sensitive areas.
• Noise Reduction Procedures: Airlines and pilots can implement procedures such as reduced thrust take-off, displaced landing thresholds, and continuous descent operations to reduce engine noise.
• Land-Use Planning: Airports can work with local authorities to implement zoning rules and encourage developments that are not sensitive to aircraft noise, such as light industry or storage areas. Additionally, providing sound insulation for homes, schools, and other buildings near the airport can help reduce indoor noise levels.
• Community Engagement: Airport operators can collaborate with neighbouring communities and user groups to address noise concerns. This can include public meetings, hearings, and providing opportunities for people living in noise-impacted areas to participate in technical and general committees.

Frequently asked questions