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What do we understand by noise, and how does it affect us?
Answering this question will help us understand and prevent a problem that affects millions of people in urban environments.
Noise is understood as a particular case of an unwanted sound. It is a sound emission generated by a vibratory phenomenon, transmitted through the air, detected by the ear, and perceived as a nuisance. It generally consists of random variations in acoustic pressure that, upon reaching the auditory system, are interpreted by the brain as an alert, triggering the release of stress hormones. This has been demonstrated in research by Professor Charlotte Clark of the University of London, reported by the BBC alongside journalist James Gallagher, where they discuss an immersive experiment observing heart responses to different noises. This experiment presents evidence that traffic noise affects the cardiovascular system.
Regarding its origin, it can be said that the main generator of noise is human activity. It is true that nature also produces noise, such as foliage rustling in the wind, waves breaking on the shore, or territorial disputes between lynxes (see this National Geographic post on surprising sounds produced by some animals).
The factors to understand are the nature of our auditory system and the environment we inhabit. Hearing is a sense over which we have no control; we cannot choose when to stop hearing as we can choose when to stop seeing or smelling. It has evolved this way for survival, allowing rapid reactions when hearing predators approaching through the underbrush. These scenarios are no longer common today, especially in urban environments where human activity is present 24 hours a day. Continuous exposure to a multitude of noises is harmful to health—a paradox that reflects the priorities of modern society.
Urban noise stands as one of the key challenges of the 21st century: science, legislation, technology, medical studies, governmental initiatives, and public communication are some of the tools available to address it. And rightly so. Numerous studies have been conducted to assess and measure the impact of noise on health, demonstrating how it can affect cognitive, emotional, and physiological development. These articles address this issue in different cities:
Noise in cities: how and why we should tackle it (Spain, 2023). This post discusses the main health problems caused by traffic in major European cities, the challenge of noise in urban environments, and proposals for its mitigation.
Road Traffic Noise and Incidence of Primary Hypertension: A Prospective Analysis in UK Biobank (United Kingdom, 2023). The purpose of this study was to evaluate the associations between long-term exposure to road traffic noise and the incidence of primary hypertension through a population-based prospective analysis in the UK Biobank.
Health impact assessment of exposure to road traffic noise and air pollution according to pre- and post-densification scenarios in Helsingborg, Sweden (Sweden, 2024). This study analyzes the health effects of noise in low-income residential areas in Helsingborg, Sweden. What makes it particularly interesting is the densification comparison it offers, including a prior scenario (2012) and a projected one (2030).
Noise pollution and vehicular traffic at the Mexico border (Mexico, 2019). This article seeks to determine the relationship between noise levels at major road intersections and the number of vehicles passing through them in the city of Matamoros, Tamaulipas, Mexico—a city located on the border with the United States.
Association between environmental noise exposure and sleep quality among adults living in Medellín, Colombia, 2022: an exploratory study (Colombia, 2022). This article reviews evidence on the effects of air pollution—particularly that associated with motor traffic—on public health.
Domestic noise exposure, emotional problems, and attention deficit hyperactivity disorder in 9-year-old schoolchildren (Spain, 2024). This study examines the relationship between household noise exposure and emotional and behavioral problems in 9-year-old children. High levels of domestic noise are associated with increased risk of neurodevelopmental disorders.
Health impact assessment of urban and transport developments in Barcelona: A case study (Spain, 2025). Another benefit of addressing urban mobility is the reduction of nitrogen dioxide levels, preventing premature deaths in the affected area.
Given the vast amount of evidence and the large population affected, actions to mitigate the impact of noise are sometimes slow, inconvenient, and even inefficient—but highly necessary. Depending on the characteristics of the noise, there are options we can adopt to improve our comfort, some very feasible and economical, while others require specialized labor and considerable patience. For all these reasons, it is essential to carry out acoustic engineering projects, in collaboration with other disciplines, to identify the main problematic noise sources and address the solution from the outset.