The quest for quiet: Can we retune the urban world?

The pitch of human-made noise has risen. See how seismic guns fired underwater are claiming lives; how trains are affecting learning levels in classrooms.

For most of us, in the pandemic, birdsong seemed to grow louder. But studies conducted since are revealing that, in some places, the opposite was true.

Flamingoes flock to Talawe in Navi Mumbai, during the pandemic. Around the world during this time, birds became more audible; some actually responded to the quiet by beginning to sing more softly. (HT Archives)

As traffic noises disappeared from San Francisco, for instance, the dramatic buzzes and trills of the white-crowned sparrow quieted — by as much as 30%. They no longer needed to shout. Instead, their songs became richer, more complex, as they warned each other of nearby predators, repelled competing rivals, or attracted mates.

Even small improvements to noise pollution can lead to the reversal of the environmental damage that man-made sound has caused, states the study, titled Singing in a Silent Spring, conducted by researchers in Tennessee and California and published in the journal Science in 2020. Such reduction could lead to demographic recovery and higher species diversity in urban areas, it notes.

For decades, we have tracked the flip side: ways in which human-made noise, or anthropophony, affect the natural world. It has been shown to cause symptoms similar to post-traumatic stress disorder in birds, thin out populations of underwater species by masking their auditory mating signals.

In humans, chronic exposure to noise at even 55 dB (about the sound of moderate traffic) can be enough to delay reading and language development in children under 10 and increase the risk of heart disease and stroke in adults.

A 1975 study found that at a New York City public school, children whose classrooms faced a noisy railway track had fallen behind in reading, writing and arithmetic ability, compared with peers on the opposite side of the building. When measures such as soundproofing were taken, the scores evened out, showed a study led by Arline L Bronzaft, an environmental psychologist at New York’s Lehman College, and published in the Journal of Environmental Psychology.

Man-made noise is not a modern phenomenon. Urban noise was prevalent so long before industrialisation that Julius Caesar, in the 1st century BCE, reportedly complained of the endless clack of wheels on Rome’s cobblestoned streets at night.

But the destruction caused by anthropophony has lately reached epic proportions.

Seismic air guns used to locate seams of oil and gas in ocean beds, for instance, emit powerful pressurised blasts of air as sound waves that reflect back off the ocean floor providing information about its geology. The reverberating blasts can be as loud as 260 underwater dB (equivalent to about 200 dB in the atmosphere; or about as loud as a sonic boom).

The air guns fire every few seconds during surveys that can run for months, over tens of thousands of square km. While larger, quicker animals flee, the marine crustaceans that form the base of the food pyramid can see entire colonies wiped out.

In a 2015 experiment off the coast of Tasmania, a single air gun blast killed all krill larvae within more than 1 km, and most other plankton.

The good news is that reducing sound pollution is an achievable target. Unlike plastic contamination, action yields immediate results.

It might help to develop a little humility too. We didn’t always dominate the soundscape.

This became evident as settlers first arrived in what is now the United States. “European settlers in America,” environmental historian Peter A Coates writes in a 2005 essay, quoting historian Mark Smith, “found the noise of an axe striking a tree an aural victory over the howling wilderness.”