Welcome to this guided walk all about noise in nature! In these sound bites, you’ll hear both information and sample sounds. Sound is all around us, both naturally occurring and human-made. However, it’s getting harder to find places with only naturally occurring sounds, such as wind in the trees, a babbling brook, or birds singing. When sound becomes unwanted or inappropriate in an environment, it becomes noise. What we hear in the natural world matters. We encourage you to take note of what you hear around you as you walk.

01 Introduction

More than 83% of land in the continental United States is exposed to noticeable vehicular noise, let alone other sources of human made noise. What is this doing to our health and our ecosystems? It turns out, a lot. Since excessive noise causes harm, it’s classified as a pollutant. The main sources of noise pollution are motorized traffic, air traffic, construction sites and neighborhood noise such as TVs or yard tools. These may seem like brief, one-time instances of noise, but they all add up to a cacophony of urbanization and development.

02 What is noise pollution?

Noise impacts may seem innocuous or minor, but they’re pervasive because of the interconnectedness of our ecosystems. In the 1990s, ecologists developed the acoustic niche hypothesis, which says that species sharing an ecosystem evolved to make sounds at different times and different pitches so they don’t interfere with each other. Amphibians, birds, insects and mammals all rely on sound to convey essential information, such as mating and warning signals. All of these fundamental behaviors are at risk if animals can’t hear properly over booming anthropogenic noise.

03 Impact of noise on animals

Many species of songbirds rely on sound for communication, including for mating. A study published in 2020 used citizen science data from the entire continental US to study noise impacts on birds over 14 years. They found that increased levels of noise in forests led to fewer eggs being laid and less successful rearing of the chicks compared to quieter forests. Birds with lower vocal frequency, such as the northern cardinal found here in Minnesota, are affected more because their songs are masked specifically by the all too common car noise.

04 Birds

Some species of bats rely on listening for the faint sounds of insects that they hunt. In the presence of too much sound, these bats are unable to locate enough to eat. This might sound great for the insects, but we must remember this can have ripple effects. Owls, like bats, use acoustic signals to locate their prey, too. The prey of bats and owls then find themselves with more competition for their own food, which puts the ecosystem out of balance.

05 Bats

In addition to animals, plants also experience the impact of noise pollution. When pollinating animals such as rodents, bats or insects are scared away due to noise pollution, the plant's reproduction is negatively impacted.

06 Plants

Noise pollution doesn’t just impact wildlife; it impacts humans negatively too. Excessive noise can cause sleep disturbances, impacts focus and attention abilities, and increases the risk of heart disease, fatigue, anxiety and depression. In children, persistent exposure to noise can impair their cognitive development, causing lifelong effects.

07 Humans

Reducing noise pollution is beneficial for humans because not only do we reduce the negative impacts of the noise but we also increase access to naturally occurring sounds! This is important because hearing natural sounds can decrease pain, lower stress, improve mood, and enhance cognitive performance. Sure sounds like a win-win!

08 Benefits

Unlike other types of pollution, noise pollution stops as soon as we turn off the source. What can you do to reduce noise pollution? Walk or bike when possible instead of driving. Switch to quieter, electric yard tools, or consider leaving the leaves and mowing your grass less often. Get creative, plant shrubs, trees or bushes as sound barriers in your community! If you’re a business owner, policy maker or city planner, don’t forget the positive impacts that reducing noise pollution can have. Many professionals can design noise-reduced streets, buildings and community spaces if you seek them out. Ultimately, knowing that noise can be polluting is the most important step. Share what you’ve learned with your family and friends!

09 Steps you can take

Take long breaths deep into the abdomen. 
Stop, stand or sit, listen to what’s around you, what can you hear?
Listen to the sounds of the forest.
Count how many different sounds you hear.
Listen for things you can see but not immediately hear.
Listen for things you can hear but not see.
If you’ve been to this place before, what do you notice is different now? 
Notice how you feel when you hear the sounds around you.
Take another long, deep breath and soak up this natural world we call home.

Noise in Nature