What if we could understand the health of nature just by listening to it? That’s now possible thanks to ecoacoustics, the scientific discipline that studies how the sounds of the environment reflect the health of the ecosystems within it. Instead of observing only with our eyes, this science invites us to listen to landscapes to detect subtle changes in wildlife, habitats, and human influence.
To do this, researchers use automatic recorders placed throughout the environment that capture sound 24 hours a day. This method allows them to collect data in a noninvasive way, as the recorders—now smaller and easier to camouflage—are installed on trees or posts, often powered by solar panels, and gather information without disturbing wildlife.
Among the sounds of an ecosystem, scientists usually analyze three main components:
biophony, or the biological sounds produced by animals such as the calls of amphibians or insects; geophony, which encompasses nonbiological sounds such as rain, wind rustling through trees, or waves breaking on the shore; and technophony (also called anthropophony), referring to the noise generated by human activity and technology—from the hum of traffic to airplanes flying overhead. Ideally, a healthy environment should have a rich balance of biophony and geophony, with minimal interference from technophony. For this reason, when scientists evaluate a habitat, they can often infer biodiversity loss or environmental degradation from its acoustic profile.
What advantages does this system offer? Unlike traditional observation methods—such as visual counts or camera traps—acoustic recordings can detect more species by sound than by sight in certain areas, especially those that are active at night. In addition, thousands of hours of recordings become historical archives, documenting what a place sounded like at a given time—an invaluable resource for comparing long-term ecological trends. Finally, because the recorders operate day and night, they provide constant, low-cost monitoring of the environment—especially important in remote or hard-to-reach areas (dense jungles, marine zones) or during periods when researchers cannot be present.
One of the most ambitious projects in this field is the Australian Acoustic Observatory (A2O), a continental network of acoustic sensors deployed across Australia. Since its inception in 2019, A2O has installed hundreds of electronic “ears” in 100 different locations, from deserts and scrublands to tropical forests. The devices run on solar energy and record ambient sound continuously, so that it can be analyzed later.
To interpret this enormous amount of sound information, scientists typically use acoustic indices—mathematical metrics that summarize features of the soundscape—and artificial intelligence. In the latter case, machine learning algorithms are trained to recognize, among many other things, the calls of specific species within the mix of environmental sounds. For example, tools like BirdNET can automatically identify hundreds of bird songs. As a result, the volume of information handled by ecoacoustic laboratories such as A2O is immense. In their case, they store around 2 petabytes of environmental audio, equivalent to 2,000 years of nonstop recordings.
Thanks to ecoacoustics, A2O scientists can track the recovery of plant and animal species after the devastating wildfires that recently struck Australia. By analyzing biophony before and after the fires, they can detect whether the songs of certain birds, the calls of nocturnal marsupials, or the croaks of frogs are returning. Experts point out that this discipline allows us to hear life returning to landscapes once silenced by catastrophe.
In conclusion, ecoacoustics may be changing the way we understand and care for our ecosystems. Every sparrow’s chirp and every whisper of wind can provide valuable information. We simply need to tune our ears to realize that the planet is speaking to us—and offering clues for its conservation. Listening to the environment, then, may be another way to protect it.