The sound of leaves rustling in the wind, water babbling down a stream, or birds chirping in the canopies can significantly improve our health, according to new research.
For their study, researchers from Carleton University, Michigan State University, Colorado State University, and the National Park Service, asked dozens of students to identify different types of sounds in a series of recordings. The soundscape database included recordings of wildlife and natural sounds -- from rain falling to wolves howling -- from 251 sites in 66 national parks across the United States.
While doing so, the researchers found that the participants experienced less pain, lower stress, improved mood, and enhanced cognitive performance. The greatest improvements in terms of positive emotions and health outcomes were associated with sounds of water, while birdsong lowered stress the most and lifted people's moods.
These findings are important more than ever in the context of this pandemic, which has seen millions cooped up in their urban homes for months on end. On the one side, not being able to visit national parks may have contributed to enhanced stress and less desirable mental health outcomes. But on the flipside, lockdowns have also slashed traffic and put the plug on urban noise pollution, allowing people to experience the natural soundscapes of their own backyards with fresh ears.
In 2017, a study led by Rachel Buxton -- an acoustic ecologist at Colorado State University in Fort Collins who is also one of the lead authors of the new study published today in the Proceedings of the National Academy of Sciences -- found protected areas are getting noisier. More than half of the protected areas in the USA are twice as loud as they should be, the study found.
This means that if you used to be able to hear a bird sing 30 meters (100 feet) away then now you would only hear it 15 meters (50 feet) away. However, 21% of protected areas were even 10 times louder than they should be so you would only be able to hear a bird that is 1.5 meters (10 feet) away. All in all, background noise reduced the distance that other sounds can be heard by 50-90%. Additionally, 58% of areas with endangered species had doubled noise levels.
The more popular a park is, the more likely it is that visitors are not reaping the full health benefits they'd have in a quiet park.
This isn't the first study that found a connection between exposure to nature sounds and wellbeing. Writing in Scientific Reports, researchers at Brighton and Sussex Medical School in England recruited 17 healthy adults to receive functional magnetic resonance imaging (fMRI) scans while listening to a series of five-minute soundscapes of natural and manmade environments.
The brain scans showed that listening to artificial sounds was associated with patterns of inward-focused attention, while nature sounds prompted more external-focused attention. Inward-focused attention can make people worry and ruminate about their daily woes, setting patterns in motion that can lead to stress, anxiety, and even depression. This study also found that nature sounds decreased the body’s sympathetic response (which causes that “fight-or-flight” feeling), helping the body relax more.
With this in mind, the authors of the new study recommend implementing programs that increase people's exposure to nature sounds, paired with noise management programs.
"Park sites near urban areas with higher levels of visitation represent important targets for soundscape conservation to bolster health for visitors," said Kurt Fristrup, a coauthor on the study and bioacoustical scientist at the National Park Service. "Nature-based health interventions are increasingly common in parks and incorporating explicit consideration of the acoustic environment is an opportunity to enhance health outcomes for people."
