If the noise of your thoughts hasn’t driven you crazy yet, the noise outside would have done it already. Vehicles revving; motorcycles zipping; people shouting; dogs barking; mobile phones ringing; construction noise; and honking from hell. Also, the devil’s preferred device: the loudspeaker through which Christian preachers save the sinners, the Hindus compete with each other in broadcasting bhajans for their gods, and Muslims call for prayer. As our cities get loud and dense, the impacts reverberate in bodies and minds.
According to a 2024 World Health Organization coordinated study, environmental noise refers to noise from various forms of traffic or industry, and also to amplified music in the framework of leisure activities. Its sources include transportation (aircraft, trains and motor vehicles), industry, wind turbines and leisure activities. It doesn’t include noise pollution in workplaces.
“Estimates for the European Union indicate that approximately 1 in 5 people, or 100 million citizens, are exposed to unhealthy levels of road traffic noise,” the study said.
A 2011 WHO report states that disability-adjusted life-years (DALY, equivalent to losing on full year of healthy life) lost from environmental noise are 61,000 years for ischaemic heart disease, 45,000 years for cognitive impairment of children, 903,000 years for sleep disturbance, 22,000 years for tinnitus and 587,000 years for annoyance in the European Union member states.
These results indicate that at least “one million healthy life years are lost every year from traffic related noise in the western part of Europe”. Sleep disturbance and annoyance, mostly related to road traffic noise, comprise the main burden of environmental noise.
If western Europe has borne that much burden then it is hard to estimate the burden Indians face from noise. A 2023 study from researchers at the Indian Institute of Technology, Guwahati, calibrates the impacts of noise on street vendors and office workers. It says that combination of particulate matter and noise pollution increased their blood pressure and heart rate. Low frequency noise —50-630 Hz—affected blood pressure and heart rate.
A 2016 study of noise around a tertiary care hospital in north India reported 74 per cent of people as having irritation and 40 per cent suffering from noise-induced headache.
Launched in 2011, India’s National Ambient Noise Monitoring Network stations report average levels of noise. As such, they are quite useful for regulation.
The Central Pollution Control Board (CPCB), as per the Noise Pollution (Regulation and Control) Rules, 2000, categorises zones as industrial, commercial, residential, and silent, and accords each a permissible noise level. For example, a residential zone has the daytime limit of 55 dB and nighttime of 45 dB.
Globally, the ill-effects of noise have been recognised for long. Noise pollution has been linked to various health problems. A 2019 review paper concluded that noise interferes with communication, disturbs daily activities, and disrupts sleep, leading to mental stress.
The paper said that noise leads to rise in stress hormone levels that can cause “autonomic imbalance, oxidative stress, inflammation, and endothelial dysfunction, which then accelerates the development of cerebrocardiovascular risk factors and disease”.
Importantly, since noise exposure reflects mental stress, it favours the onset of psychological symptoms and disorders, which in turn is associated with cerebrocardiovascular dysfunction, highlighting the interrelationship between mental stress and psychological disorders and cerebrocardiovascular disease.
The biggest problem here is that there are different sources of noise, said Aditya Kamineni, associate professor, department of civil engineering, J B Institute of Engineering and Technology (JBIET), Hyderabad. He has worked on highway traffic noise pollution, tyre-road interaction, among others.
Aditya said there are different aspects to noise pollution from traffic. There is honking, a number of horns per second or per hour. The next is propulsion noise which is the noise coming from the engine, gear shaft, and the transmission unit of a vehicle. Then there is aerodynamic noise, the sound that a vehicle makes as air collides with its forward motion. There is also the noise generated by interaction between vehicles tyres and road surfaces. All four contribute to noise pile-up.
Aditya said with EVs, the the engine propulsion noise is lesser. “But the tyre-pavement interaction is something that is common and you cannot avoid that noise,” he said.
As a transportation engineer, his intention was to quantify noise as well as propose something lowers noise levels.
A lot of highways in India are black-topped bituminous roads. Bitumen is a waste product from petroleum process whereas tar is from coal. In his surveys at Hyderabad, Vijayawada, Warangal and other places, he found that the concrete roads, mostly found in villages, generate the highest noise levels at different speeds compared to the bituminous roads.
Experts working on these matters say the optimum way to reduce vehicular noise pollution is to construct roads that nullify the noise. It could be a combination of bitumen and rubber, plastic-modified bitumen roads, among other materials.
The key is to increase the porosity of roads so it tamps down the noise.
Imagining a scenario 15 to 20 years from now when at least 70 percent of the vehicles are electric, Aditya said, it will definitely result in a reduction of propulsion noise. However, planners have to worry about tyre-pavement noise. “So, you have to work on construction of noise-reducing roads,” said Aditya.
Next time you’re in the verge of a noise-induced headache, remember what the American composer and music theorist John Cage said: “Wherever we are, what we hear is mostly noise. When we ignore it, it disturbs us. When we listen to it, we find it fascinating.”
