Extracts from Why Noise Matters (2011)
by Stewart et al
The threat to the planet’s sound systems is silently passing the world by
This blog makes the case for noise as a green issue. It draws a parallel between the way in which climate change is threatening to alter the planet’s eco-systems and ‘man-made’ or human noise is threatening the planet’s natural sound systems. These natural systems, which have evolved over the centuries, are fragile and complex. The sounds of the oceans, the forests, the deserts and the prairies send important signals to marine and wildlife. When human noise distorts or destroys these sounds, the very survival of the species which depend on them can be threatened. Although there is some evidence of adaptation to new, noisy situations – such as urban birds singing more loudly – there are also signs that human noise has become so intrusive that it is threatening to destroy the delicate balance of nature’s sound systems on which so many species depend. As a general rule, the noise impact on marine and wildlife depends on the extent to which noise disrupts a functioning eco-system or a natural sound system.
Noise has the greatest effect on the marine and wildlife which rely most heavily on auditory signals for survival. Increases in background noise levels can interfere with, or mask, communication signals which animals, birds and mammals use in their daily lives: in courtship, to warn of danger (often critical to survival) or to stake out territory.
It is in the oceans and forests that the natural sound systems are being most dramatically distorted.
The natural sounds of the ocean are magnificent in their range, beautiful in their delivery and stunningly varied. But these sounds are in danger of being overwhelmed by human noises and vibrations as never before in recorded history. It is estimated that during the past 50 years underwater noise has doubled each decade. Scientists and conservationists are increasingly concerned that noise pollution poses a significant threat to whales, dolphins and other marine wildlife.
The sounds of the jungle rival those of the ocean. They are at once beautiful and frightening, awesome and awe-inspiring. But they are under threat. As the jungle is chopped down or invaded, its natural noise rhythms are disappearing. Dr Bernie Krause, the eminent American acoustician who has recorded nature’s sounds for the past forty years, estimates that in that time nearly a third of the ecosystems he has captured have become aurally “extinct” because of habitat loss or the presence of noise-making machines .
Sonar testing is having an impact on mammals and fish.
However, it is ships which are responsible for the majority of the human-induced noise in the oceans. The noisiest ships are the huge vessels which carry oil, food and manufactured goods between ports all over the world. It is the propellers which are the cause of most of the noise from ships. As the blades turn, they create thousands of tiny bubbles, a process known as ‘cavitation’. It is the sound of these bubbles bursting which causes the noise. Ship engines are a distant secondary contributor.
We are all familiar with the phase ‘dumb animals’. It comes from the days when we assumed that animals couldn’t talk to each other. We now know differently. Dr Bernie Krause, the musician turned acoustician, coined a word for this: biophony. It is what the world sounds like in the absence of humans. It is quite remarkable. Krause has found that animals divide up the acoustic spectrum so they don’t interfere with one another’s voices. It is like a musical score for an orchestra, with each instrument in its place. No two species are using the same frequency. Krause told Wired Magazine: ‘That’s part of how they co-exist so well.’ When they issue mating calls or warning cries, they aren’t masked by the noises of other animals. This is best illustrated in the rainforest.
When human noise - what Krause calls anthropony – intrudes on this natural symphony, the information flow of the animal world is disturbed. It is increasingly happening: from cars, lorries, aircraft, logging, drilling. It doesn’t take much to disrupt the delicate balance of a natural soundscape.
It is interesting, though, that this threat to the planet’s sound systems is silently passing the world by. Though there is concern amongst individuals and some campaigning groups, it has generated nothing to match the vibrant, worldwide movement urging action to stop runaway climate change. The lack of interest is almost certainly a by-product of the way that society has failed to tackle noise problems closer to home over the past decades. Noise hasn’t been regarded as a major pollutant. It still isn’t seen as a key problem. But nature is telling us something different. How long will we remain deaf to its dying call?