Photo credit: Brayden Donnelly – braydenndonnelly.weebly.com

Prime hiking season is upon us, and with that comes overgrown trails, new growth, wild flowers, and all the sounds that we find in nature.  Whether it’s the wind through the trees, the chatter of animals, the movement of water, or the noise of nothingness that just seems to exist naturally; these sounds make up what I like to call nature’s white noise.  In April, I wrote about Shinrin-yoku, the Japanese practice of forest bathing; this month I’d like to explore the sounds that we hear in nature and how those noises both play a role in why nature makes us feel good and how we play an active part in that.

As people, we assign meanings to sound which trigger psychological and physiological responses within us.  For example, if during a hike, you hear the roar of a big cat, what happens?  Does your heart speed up and you begin to sweat?  Do experience a state of mild panic, as you realize that that means there is a large cat in the area?  Do you head back down the trail?  As humans, we have assigned ‘danger’ as the meaning to hearing a large cat in the wild.  Therefore, when we are in the wilderness, and we hear the cat, our brains register danger and our autonomic nervous system, which controls our fight-flight reaction, is activated.  This activation then causes our heart to speed and our respiratory rate to increase; we get a shot of adrenaline, and our mind/body experiences different reactions associated with potentially being in danger.

Photo credit: Brayden Donnelly – braydenndonnelly.weebly.com

In his book The Audible Past, Stern (2003) explains, the meaning we assign to sounds, including sounds in nature, come from both the society we live in and our personal experiences (12).  Therefore, the meanings we assign are not only created and perpetuated within our societies but are also individualized based on our experiences.  For example, I was once sniffed through a tent by a black bear in the Appalachians; it was hands down one of the most terrifying experiences of my college life.  Now, whenever I’m sleeping in a tent, I still have a fight-flight reaction to any critter that I can hear…even if it’s just the neighbor’s dog!

So now the question becomes, what is the science behind what happens when you listen to nature sounds, and what is the mental heal connection?

The Science

In a collaboration between artists and scientists, a research team at Brighton and Sussex Medical School designed an experiment that utilized neuroimaging and pulse oximetry to measure physiological reactions while participants listened to silence, artificial sounds, and naturalistic sounds (University of Sussex, 2017).  While participants listened to these different soundscapes, the research team watched to see if the participants demonstrated an improved ability to focus (attention capacity), and if there was a balancing in the autonomic nervous system between the fight-flight activation with the rest-digest activation (occurs when we don’t sense danger), while listening to natural sounds (Gould van Praag et al., 2017).  Here’s what they found:

• Focus: The research found participants had poorer focus while listening to artificial sounds, and better focus when listening to natural sounds.

• Balancing Activations. Neuroimaging and pulse oximetry showed a shift from the fight-flight activation to the rest-digest activation while listening to naturalistic soundscapes.

• Default Mode Network. The default mode network is comprised of regions of the brain that are active when we are awake but task free; it’s been compared to being “offline.”  This study revealed that the activity in the default mode network of the brain was different depending on which of the sounds the participant was listening to (Gould van Praag et al., 2017).  This demonstrates that even if we’re out hiking and we’re enjoying the moment, something like road noise, or another hiker carrying a portable speaker playing music can fundamentally affect how we interact with nature.

The Mental Health Connection

Imbalance in the autonomic nervous system that features heightened sympathetic (fight-flight) activation and decreased parasympathetic (rest-digest) activation, is associated with psychological and physiological stress.  Chronic stress caused by the autonomic nervous system imbalance is detrimental to health and can contribute to cardiovascular disease, cellular aging, obesity, gastrointestinal disorders, and a “spectrum of mental health conditions, particularly depression and anxiety disorders” (Gould van Praag et al., 2017).  In Gould van Praag et al., study, participants that showed the greatest amount of stress before starting the experiment were the most relaxed while listening to natural sounds (University of Sussex, 2016).

Photo credit: Brayden Donnelly – braydenndonnelly.weebly.com

The research also demonstrated that when participants listened to natural sounds, brain connectivity showed an outward-directed focus of attention; by contrast, when artificial sounds were listened to, brain connectivity showed an inward-directed focus of attention.  Similar states of inward-directed focus are seen in anxiety, post-traumatic stress disorder, and depression.  The results of this study suggest that listening to naturalistic sounds, which decrease inward-direct brain activity in the subregions of the prefrontal cortex, may be beneficial (Gould van Praag et al., 2017).

The Next Time You’re Out

The next time you’re out in nature or the wilderness, take a mindful listen to the noises around you.  By just listening to nature’s white noise, you can gain some positive mental health benefits.  However, I’d also encourage you to take note of what you hear and how your body and mind react.  As you experience this, ask yourself what do those sounds mean to you?  Why do you think that sound holds that meaning to you? What is it about that sound that caused you to have that reaction?

Let me know about your adventures, nature’s white noise, and your assigned meanings in the comments!

Photo credit: Brayden Donnelly – braydenndonnelly.weebly.com

References

Gould van Praag, C. D. et al. (2017). Mind-wandering and alterations to default mode network connectivity when listening to naturalistic versus artificial sounds. Sci. Rep. 7, 45273; doi: 10.1038/srep45273.

Sterne, J. (2003). The Audible Past: Cultural Origins of Sound Reproduction. Durham: Duke University Press.

University of Sussex. (2017, March 30). It’s true: The sound of nature helps us relax. ScienceDaily. Retrieved May 18, 2017 from www.sciencedaily.com/releases/2017/03/170330132354.htm