The Sound of Cities How noise contaminates our cities and threatens our health

Read more Last updated: November 2020
In collection Kids
Reading duration: 8 minutes

The cities of the world are shaped by different noises. Each has its characteristic sound, which is not always pleasant. Conurbations are increasingly struggling with noise contamination. This has been shown to have significant negative consequences for health, safety, and general quality of life. Thus, and not least because the world is becoming increasingly urbanized, smart solutions are required to battle noise.

Every city has a soundtrack

From east to west and north to south: the world's cities' soundtracks are as individual as their inhabitants. While the trams pass the sights in Lisbon, in London, the tube roars through the city underground. New Jersey is more influenced by traffic noise than New York, where human voices, in particular, contribute to the urban sound. When we visit old cities like Rome or Madrid, the voices are accompanied by music.

A few years ago, a group of researchers created a map for 12 cities in the US and Europe to show which noises make up the places' sound and which emotions they evoke. Chatty maps allow an acoustic stroll through London, Washington, or Barcelona, among others. Each street can be clicked on individually and is provided with data: on the Rambla, for example, traffic noise and noise from buildings only make up around 20 percent. More than 30 percent are human voices, almost 27 percent natural sounds, and about 23 percent music – sounds that arouse trust, joy, and anticipation. However, on Canal Bank Drive in Chicago, fear, anger, and sadness predominate, triggered by traffic noises of 99 percent.

The loudest and quietest cities in the world

Cities differ not only in terms of their typical noises. Their noise levels also vary greatly, as a global study conducted in the wake of the World Hearing Day 2017 with over 200,000 participants shows. The results were compiled in the Worldwide Hearing Index: The Swiss capital, Zurich, has the lowest noise contamination. Guangzhou in China has the highest.

City noise damages our hearing

According to the WHO, noise contamination poses a serious risk to our health and well-being. It is increasingly affecting everyday life at school, at work, and at home.

What is noise contamination?

Noise is omnipresent in cities. If we are exposed to it regularly and over a more extended period, this has negative health consequences. Up to 70 decibels are harmless even over long periods. Still, from 85 decibels over about eight hours a day, it becomes dangerous. In a city, it is often hardly possible to distance yourself: if you live or work near a busy street, you are exposed to the noise of 85 decibels for a large part of the day.

The following sources typically contribute to noise contamination:

  • traffic noises from buses, trains, ambulances, but also pedestrians
  • airport operations
  • station operation
  • industrial noise
  • construction site noise
  • loud music at concert venues and in the surrounding areas
  • other noises at events, such as fireworks
  • workplace noises, e.g., in open-plan offices
  • neighborhood noises: TV noises, radio, washing machines, vacuum cleaners, air conditioners, lawnmowers, etc.

Health risks

Noise has been shown to endanger our health in many ways. Problems caused or enhanced by noise contamination include:

  • high blood pressure
  • cardiovascular disorders
  • sleep disorders
  • noise annoyance
  • developmental Disorders in Children
  • mental illness, e.g., Depression
  • dementia

Noise and hearing loss are linked

The study mentioned above from 2017 also suggests a direct connection between noise contamination in cities and hearing loss. There is a correlation of 64 percent. People living in metropolitan areas can assume that their hearing ability does not match their real age. For example, London women have the hearing of a person 15.5 years older, and London men have a 14-year difference. While the Viennese enjoy comparatively good hearing, many New Delhi residents are affected by hearing loss.

According to the UN, our world is becoming more and more urbanized. It is expected that just over 65 percent of the world's population will live in cities by 2050; currently, it is already 55 percent. The more people move to cities, and rural areas are urbanized, the more urgent becomes the question: How can we make our cities healthier, safer, and more pleasant?

Hearing loss in the city – a safety risk

Hearing skills and personal security go hand in hand, and especially in big cities. A threat is often perceived acoustically before we even see it. This includes cars and motorcycles and bicycles or a potentially threatening person who approaches us. Hearing alone is not enough: We need good hearing to filter out all the different sounds from the urban background noise. On the one hand, balanced hearing allows us to identify the direction from which a threatening noise is coming. On the other hand, we can estimate how far away the source of the noise is. Persons who only hear (well) in one ear do not have this advantage and are exposed to an increased risk.

Personal safety is but one side; the other is the acoustic diversity that people with hearing loss have to do without every day. For example, due to background noise, they can no longer perceive the already sparse natural noises such as birds' chirping or wind in the treetops. Yet these are noises that have been proven to be beneficial to health. They also miss conversations between other people, which are what makes a stroll through the city really fascinating.

Noise reduction is essential

According to the WHO, over 430 million people are affected by hearing loss. If the forecasts prove right, there will be twice as many in 30 years, partly due to noise pollution in cities. Suppose we want to prevent this and ensure the safety and health of the population. In that case, we have to develop concrete concepts for noise reduction in the cities.

Unfortunately, global noise policies are relatively weak, as for example in the USA and Great Britain. According to an Environmental Noise Directive, the EU is pursuing strategies based on which noise is to be identified and combated. In addition to aircraft noise and neighborhood noise, road and rail traffic noise should also be reduced. Corresponding measures include traffic calming through speed restrictions, pedestrian zones' implementation, and play streets or structural measures such as partial paving and speed bumps. Noise barriers on busy main roads and on railway lines are also being used more and more.

Modern building materials offer further possibilities: silent asphalt, also known as open-pored asphalt, has a noise-reducing effect. During production, coarse-grained gravel is mixed with a lower proportion of modified bitumen than regular asphalt, creating cavities. These divert some of the air between the car tires and the road surface and thus minimize noise. Whisper rails for trams, in turn, have a rubber coating and hence an insulating effect. The difference to standard rails cannot be measured in decibels. Still, since at least the vibrations are attenuated, there is a positive effect for residents.

In addition to the measures already mentioned, switching to electromobility will undoubtedly help to minimize traffic noise. Planting more trees and creating green spaces is also important. They can reduce ambient noise by five to ten decibels and provide a home for birds and other animals, evoking positive emotions with their noises. Another possibility is to mask undesired sounds. For example, with a fountain, the water's splashing blocks the street's noise, and we perceive the ambiance to be much quieter than it actually is.

The sound of the city reimagined: innovative measures

Reducing noise is an important task, but there is so much more to be done. The perception of noise is individual, and a certain amount of noise is also part of city life. In the wake of the global pandemic, some New Yorkers report that they miss the honking of cars. While cities are busy tackling noise, they shouldn't overlook the positive effects of individual sounds. Not only the Chatty Maps research team takes this approach. R. Murray Schafer, sound researcher and the godfather of acoustic ecology, has been campaigning for sustainable acoustic design in urban spaces since 1977.

How artists can enhance urban soundscapes

Therefore, sound design is paramount: How can we minimize the noise in cities and create an overall more pleasant soundscape? According to Marcel Cobussen, Professor of Auditory Culture at the University of Leiden, cities and urban planners should commission sound artists to upgrade cities acoustically. In the first step, the artists would have to study their acoustic environment, employing sound walks, installations, or field recordings. Based on their findings, they could develop alternatives in the second step. They could amplify previously superimposed noises, block out unwanted noises, and add new ones. Consequently, they might create a balanced urban soundscape beneficial for the city dwellers' health and well-being.

It’s up to us!

Cities are undoubtedly responsible when it comes to noise reduction in favor of a better quality of life. However, we must not forget that we, too, contribute to the background noise in our neighborhood, at work, and during leisure time on an individual level. Must we use the leaf blower, or could we possibly rake the leaves in the garden? Do we really have to print every single memo? Do we have to take the car every day, or might the bike be the better choice? By checking our behavior and adopting new habits, we do not only ensure a pleasant acoustic experience. Lots of noisy activities also damage the climate. Thus, our battle against noise is indeed a battle for our environment – and a battle for better hearing.


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