The sounds of nature are rapidly being silenced and will become “acoustic fossils” unless urgent action is taken to stop environmental damage, international experts have warned.
As technology develops, sound is becoming increasingly important as a means of measuring ecosystem health and biodiversity. Our forests, soils and oceans all create unique acoustic signatures. Scientists who use environmental acoustics to measure habitats and species have found that thousands of habitats have gone silent due to abnormal declines in species density and diversity across the planet. It says that there are. Many familiar sounds also disappear or lose volume at the same time, such as the morning calls of birds, the rustling of mammals digging through the underbrush, and the chirping of summer insects.
Professor Steve Simpson from the University of Bristol said that tuning into some ecosystems now reveals a “deadly silence”. “It's a race against time. We just discovered that they're making those sounds, but we can hear them fading away.”
“Changes are profound. And they're happening everywhere,” said Bernie Kraus, an American soundscape chronicler who has made more than 5,000 hours of recordings from seven continents over the past 55 years. He estimates that 70% of his archives are from habitats that no longer exist.
Professor Brian Pijanowski of Purdue University in the US has been listening to nature sounds for 40 years, making recordings from nearly every major type of ecosystem in the world.
He said: “Sounds from the past that have been recorded and preserved represent the sounds of species that may no longer be here, so that's all we know. The recordings that many of us have [are] Places that no longer exist and we don't even know what those species are. In that sense, they are already acoustic fossils. ”
Numerous studies have now documented how nature's soundscapes are being altered, disrupted, and silenced. A 2021 study of 200,000 sites in North America and Europe, published in the journal Nature, found that “changes in species richness and richness have increased acoustic diversity and soundscapes on both continents over the past 25 years. It was found that there was a widespread loss of strength. The authors added: “One of the fundamental pathways by which humans interact with nature is in chronic decline, with potentially far-reaching implications for human health and well-being.”
Changes in ecosystem sound are occurring in the air, forests, soil, and even water. During the Cold War, the U.S. Navy used underwater surveillance systems to track Soviet submarines, but they found it difficult to track them near coral reefs because of all the sounds they made. It was not until 1990 that private scientists were able to hear this sensitive data.
“Every time I go to a healthy reef, I'm struck by the cacophony of sounds I hear,” said Simpson, who has been monitoring coral reefs with hydrophones for more than 20 years. “A healthy coral reef was a carnival of sounds.”
While noise pollution from motorboats was a major concern at the beginning of the study, significant bleaching events occurred in 2015 and 2016, resulting in the death of 80% of corals. “They cooked the reef,” he said. Since 1950, more than half of the world's coral reefs have been lost. It is predicted that when global warming reaches 2 degrees, more than 99% of coral reefs will begin to die.
The result of these bleaching phenomena is “deadly silence,” Simpson said. “We swam around the reef wearing masks and crying.”
“These sounds and silences speak to us like a mirror,” says Hildegard Westerkamp, a Canadian acoustic ecologist who has been documenting soundscapes for half a century. During that time, wild animal populations have declined by almost 70% on average.
She began working on the World Soundscapes project in 1973 with the aim of documenting disappearing ecosystems. “We proposed that we start listening to the soundscape in its entirety, no matter how unpleasant it is – no matter how unpleasant the message.”
She said: “The very act of listening can be comforting or deeply unsettling. But most importantly, it tends to connect us with the reality that we are facing. That means there is.”
Audio data is now being used alongside visual data as a way to monitor conservation efforts and ecosystem health. With growing concerns about environmental damage, more sophisticated and inexpensive recording equipment is driving a boom in environmental acoustic monitoring.
As microphones become more sophisticated, scientists are using them to monitor life forms that are normally inaudible to human ears. Swiss acoustic ecologist and sound artist Marcus Mader has been studying the noises trees make under stress by shoving microphones into the bark of trees to listen to living tissue. Stress sounds like a pulse coming from within a cavity, he said.
When he first pushed Mike into the soil of a mountain meadow, he discovered that it lived with noise, a “whole new kingdom of sound.”
Farmland that is intensively managed and sprayed with pesticides sounds very different, Mader said. “The soil becomes quiet.”
For many researchers, disappearing soundscapes are both a source of scientific interest and sadness. “It's sad that we're doing this, but it also helps tell a story about the beauty of nature,” Pianowski said. “As a scientist, it's hard to explain what biodiversity is, but if you play the recording and say what I'm talking about, these are the voices of this place. You can work to save it, or you can choose not to.
“Sound is the most powerful emotional trigger for humans. Acoustic memory is also very strong. I think about it as a scientist, but it's hard not to get emotional.”
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