What is sound pollution? Sound pollution is an unintentional bi-product of urbanisation, transport, and industry. It is relevant almost everywhere on the planet and there are very few places with no sound pollution.
Some may think that sound pollution is not dangerous, that is does not obstruct wildlife’s health and wellbeing, but how wrong that is. Sound pollution is an invisible danger, both on land and in our oceans.
Sounds that reach 85 decibels or higher can damage humans’ ears, and everyday things like lawn mowers, subway trains and music concerts exceed the recommended amount from the World Health Organisation. Sound pollution affects millions of people on a daily basis, and those exposed to constant loud noise can suffer from noise-induced hearing loss, high blood pressure, heart disease, sleep disturbance, and stress. Not only this but it effects all age groups including children.
However, humans are not the only species suffering. All over the world animals are being affected. Many animals rely on sound for communication, navigation, foraging, attracting mates and to avoid predators.
An example of animals being affected are birds. Birds rely on their sound to communicate, attract mates, defend territory, and warn for predators. However, due to increases in sound pollution it is creating hardships and hindering their natural instincts. This forces them to adapt and alter their behaviour. In urban habitats, bird diversity and abundance has been shown to decline as a result of chronic noise levels around cities and along roads.
Species have demonstrated adjustments to their vocal behaviour in an attempt to adapt to the cacophony of human noise. Even in Dorset, we have large urban areas such as Bournemouth and Poole. In these types of environment birds such as robins have been found to sing at night rather than in the day. This is because noise levels are too high for their calls to be heard during the day. Birds are having to adapt quickly, raising their lowest song notes in response to road noise, because most urban noise is of a low frequency. Birds are having to effectively shout in order to be heard, and in some cases this has been described as screaming. However, if some birds like pigeons, sparrows and starlings don`t adapt quickly enough they will become extinct in certain areas. One group which has been suffering population declines of two thirds in Britain in the last few decades are house sparrows. This species has a significant low-frequency component to their songs, and are unequipped to contend with the excessive noise levels in our society created by human activity.
Researchers have found that some of this noise creates stress resulting in PTSD symptoms in birds. This leads to an increase in the hormone corticosterone, resulting in health defects such as stunted growth, fewer feathers and issues with reproduction. A bird’s ability to be heard plays a direct role in its reproductive interactions and survival. Sound pollution affects birds' mating habits, which impacts population size. Noise is drowning out or altering the male bird’s song impacting both the female and males response. The outcome of noise on bird populations results in less chicks being born. Birds' ability to hear predators is also jeopardised due to the noisy surroundings. Ultimately, noise pollution diminishes the quality of habitats because fewer birds opt to stay in noisy habitats, resulting in a further reduction in places for birds to live.
Another species affected by noise pollution is bats. Bats rely heavily on sound and hearing and when noise pollution interferes with their ability to hear, their survival is at risk. A bat’s sense of hearing is between 20Hz and 120,000Hz, which is much higher than a human due their lack of visual stimuli particularly in hunting and navigating. As a result, the impact of noise on bats is far greater than that experienced by humans. Bats use echolocation to locate prey, so noise pollution subsequently means they can`t do these things. It has been found that in noisy areas bats are less active, resulting in declining numbers.
These animals are not the only ones being affected; marine mammals are also suffering. Marine mammals (cetaceans) use sound for foraging and hunting, vocal behaviour and socialising, navigation, locating partners and exchanging warning calls. Animals like whales are having to modify their behaviour by singing longer than normal in order to compensate for the noise interference. Modification to cetacean's communication, like dolphins, has resulted in reduction of group cohesion, proving that sound pollution is having a negative effect on marine mammals’ ability to communicate accurately.
The louder background noise can mean that the animals effectively have to shout, using more energy as a result. When using more energy, the demand for food increases and finding food in a noisy environment is already made difficult. This risks the animal’s health and affects its ability to care for young. Not only this but the noisy environment causes stress for the animals and can create permanent damage to the animal's hearing. This may cause animals such as whales to change their diving pattern as a panic response, causing the condition known as decompression disease or `the bends` (divers can get this when surfacing too quickly). Endangered species such as North Atlantic right whale are affected by very high levels of shipping traffic. This not only affects vocal behaviour, but it may be linked to the stranding of cetaceans.
There is a consensus that military sonar exercises have contributed to mass strandings and there is evidence that past strandings have coincided with military sonar exercises. Other sea creatures are being affected, freshwater fish and invertebrates like crabs and eels exposed to ship noise are showing anti-predator behaviour, increasing their risk of predation. I have had personal experience of seeing a dead dolphin stranded at Worbarrow Bay, in Dorset. This, along with the high levels of litter washed in on beaches such as this shows that no part of the coastline in unaffected by man’s activities.
We have been aware for many years of the impact of pollution on humans, including the effects of noise pollution on health and wellbeing. However, we are only just becoming aware that animals are affected in very similar ways. Even in Dorset, traditionally seen as a rural county these effects are being recorded. Huge increases in traffic volume and growing urbanisation is changing our region. However, Covid-19 gave a temporary pause to this, showing encouraging signs of restoration for those animals affected. This has proven it is possible to slow down this ever-growing issue. We need to act now to protect Dorset’s wildlife.