A site explored in the study. Credit: Katie Turlington
Head down to the local river, lake or creek and you’ll be greeted with a cacophony of natural sounds, from croaking frogs, to buzzing insects and the bubbling of running water.
Researchers are studying the soundscapes of these freshwater ecosystems to reveal what’s happening beneath the surface.
“The problem is that listening-in is not as simple as it sounds,” says Katie Turlington, a PhD candidate at Griffith University’s Australian Rivers Institute.
“Scientists drop waterproof microphones into rivers to record what is happening underwater. But in just one day, a single recording could capture tens of thousands of sounds and manually analysing them could take a trained professional up to 3 times longer than the recording itself.”
Waterbug chorus with fish grunts. Credit: Katie Turlington
Turlington and her colleagues have developed a free tool to help researchers wade through the noise of these huge datasets more easily.
They did it in R, a free program used to analyse data, so the tool doesn’t require advanced computer skills to operate.
Users simply upload a folder of audio files and select the most appropriate combination of variables for their own dataset and ecological context.
The tool then scans through the audio to sort similar sounds and group them together based on the time, frequency and amplitude of the signal.
A graph showing how groups of sounds overlap. Credit: Katie Turlington
This streamlines the process of identifying the sounds which have been captured in the audio.
“It can even detect sounds that become masked by the constant noise of flowing water, which often makes recordings from rivers harder to analyse,” Turlington says.
“When tested in South-East Queensland streams, the tool correctly identified nearly 90% of distinct sounds, faster and with far less effort than manual analysis.”
Turlington hopes the tool could change the way freshwater health is monitored.
“By listening to rivers, researchers can track changes in biodiversity, detect signs of disturbance, or even discover new species,” she says.
“And because sound can be recorded day and night, in remote or murky waters, it offers a low-impact way to track changes in aquatic ecosystems.
“We’ve only just started to explore freshwater sound. Making this tool publicly available and free means more people can get involved, ask questions, and hopefully make new discoveries.”
A site explored in the study. Credit: Katie Turlington
And, while the tool has been tested in underwater soundscapes so far, the researchers note it can be used to analyse sounds in all kinds of ecosystems.
“Our method enables exploratory analysis without the need for reference databases or pre-labelled data, making it ideal for underexplored ecosystems,” they write in a paper presenting the tool in the journal Methods in Ecology and Evolution.
“Our protocol could be widely scaled — this method could work with very small datasets or vice versa (provided access to adequate computing resources for big data). This scalability makes it relevant to an extensive range of ecoacoustic researchers.”