Thousands of animal and ambient sounds from eleven western states have been recorded and archived in a digital library in Utah. While fascinating in their own right, sounds can also be used to track environmental change.
Some people like to hunt animals, not to kill them, but to record the sounds they make.
Conservationists, scientists, volunteers, and state and federal agency employees have contributed over 2600 animal sounds that are now housed at the biggest library of its kind in the west, called the Western Soundscape Archive. The project was founded by recording engineer Jeff Rice and digital librarian Kenning Arlitsch in order to document the sounds of animals living in the west and to make people aware so they will want to protect the environments where these animals live.
The digital sound archive is kept at the University of Utah's J. Willard Marriott Library. Anna Neatrour was a project manager for a grant from the Institute of Museum and Library Services, awarded to Rice and Arlitsch, to develop the archive.
"The Western Soundscape Archive is a site that collects animal sounds centered on eleven states in the American West," says Neatrour. "And it provides a really good overview of all the species that live in our states as well as ambient sounds for National Parks. Quite a variety of sounds that people can listen to from their computers."
While the project no longer has funds to collect and annotate new sounds, Neatrour says archiving animal sounds is important because when people think about environmental issues and declining landscapes, they usually think about the visual aspects.
"The sounds associated with these natural landscapes change as well. So preserving that now for the future is very useful," she adds.
But recording the sounds is not always easy. Many animals are active early in the morning and can be in hard to reach locations. Different microphones are needed for different jobs. By using a parabolic microphone it's possible to pick up weak sounds from a few meters away, while a small remote microphone can be dropped into burrows in the ground, or holes in trees. Some sound enthusiasts go even further.
"If you search the archive for 'ant interview,' you can hear a story of a scientist describe how he recorded the vibrations that ants make by holding them between his teeth," says Neatrour. "It shows how devoted people are for capturing these sounds.
The recordings include over 500 bird species, 300 mammals, dozens of snakes, turtles, lizards, and frogs, as well as multiple insects. Many of the recordings are paired with predicted species distribution maps and pictures of the animals, which can be found by common or scientific name.
"We have some sounds from animals that you think would not make sounds, like earth worms for example," explains Neatrour. "And in that case the sound for that sound clip, it's more like the dirt falling as the earthworm moves through the ground."
The individual animal sounds are important, but so are collections of sounds from particular landscapes. These collections, or soundscapes, include sounds of animals, geophysical features such as wind and streams, and human-produced sounds collected over the course of a day from different locations in the natural world.
Soundscapes are frequently represented visually as spectrograms. The images of daily acoustic patterns can be used to better understand the area's biodiversity and health. Donated by the National Park Service, there are over 10,000 spectral images from 24 National Parks in the Western Soundscape Archive.
"You can actually look at these sound wave graphs and pinpoint things like airplane flights going overhead and disrupting the landscape versus variations in the ambient noise you might get in the different season," says Neatrour. "So that is something that can appeal more if people are doing research in that area."
Scientists are realizing that the auditory environment is as important as the visual landscape in understanding the health of an ecosystem. And the National Park Service is actively searching for ways to better protect the natural environment from the impact of human sounds, since studies suggest the acoustical environment is important for animals to find mates, protect their young, and to communicate about territories.
So the next time you are out in nature, remember to listen as well as look.