GENEVA — A musician and PhD in bioacoustics, Bernie Krause is on a mission to create a systematic organisation of the landscape of sound signatures. He sums it up this way: While a picture is worth a thousand words, a soundscape is worth a thousand pictures.

“There was a time when I considered natural soundscapes to be just worthless artefacts," Krause, 75, says. "I was wrong. What I have learned from my encounters with nature and its soundscapes is that, if you listen carefully, they provide you with an extremely effective tool with which to evaluate the health of a habitat across its entire spectrum.”

For Krause, a soundscape is, first and foremost, an aggregate of sounds which are captured and then displayed according to their wavelength.

This type of display is the sound signature of a landscape and each landscape has a unique sound signature. This is known as a soundscape, a portmanteau word coined by another pioneer of ecological acoustic research, Raymond Murray Schafer.

Krause considers a soundscape to be the product of three component parts: the geophony, the biophony and the anthrophony.

The geophony is made up of all the sounds that emanate from the Earth itself such as avalanches, thunder, lightening, the sound of wind in the trees and waves in the ocean. The biophony includes all the sounds produced by wild animal species. As for the anthrophony, it is all of the sounds humans make.

The combination of these three sources constitutes the soundscape. And for the past several decades, Bernie Krause has combed the planet's countryside in order to collect as many recordings as possible.

A brand new field

After years of study, however, it is actually becoming more difficult. “When I began recording these soundscapes, 40 or so years ago, I could record for 10 hours and collect one hour of usable material for an album, a film soundtrack or for a museum exhibit. Now, due to global warming, resource extraction, human noise and other factors, it takes 1,000 hours of recording to achieve the same result.”

What Krause finds most troubling is the silence, or the reduction in density of a soundscape. He cited the example of Lincoln Meadow, in the Sierra Nevada Mountains, as evidence of this. In 1988, a forestry company convinced the Lincoln Meadow residents that their planned program of selective logging of the forest would not have any appreciable impact on the landscape. Before the inhabitants gave their consent, Krause recorded the landscape’s sound signature. Twelve months and one selective logging of the forest later, he showed us two photos of the area. There was no appreciable difference. Had the operation been successful? One would think so. What did the sound signature say? Krause played for us 30 seconds or so of the recording from before and then after. The recording was supported by two comparative spectrograms. The finding was that the birds of Lincoln Meadow had been all but silenced.

Visually, the ecological impact of logging is negligible. “However, our ears tell us an entirely different story.”

Krause is making a plea that landscape research include the sound element in their studies. In February 2012, the Global Sustainable Soundscapes Network (GSSN)* was founded by Professor Bryan Pijanowski of the Foresty Department at Purdue University, based largely on the model proposed by Krause. Its objective is to bring together ecologists, acousticians, biologists and artists to coordinate and launch extensive studies into landscape acoustics. A team of researchers is now laying out the structure of a whole new scientific field: “soundscape ecology.” They are focusing on what sounds say about an area.

“Hearing sounds or not hearing them is an important factor in environmental change," said Pijanowski. "We want to understand whether sounds could be an indicator of an ecological system under threat.”

Listen below to a soundscape from Puerto Rico:

*Correction: due to an error in the original French-language version, an earlier version of this article incorrectly stated that Krause's organization, Wild Sanctuary, founded the Global Sustainable Soundscapes Network. In fact, it was founded and implemented and funded by Bryan Pijanowski of the Forestry Department at Purdue University.