Noise pollution makes the sound of silence more elusive

Planes, trains, cars, radios and so much more all add to the background noise that follows us around throughout the day.

Can you remember the last time you were in a place that was truly quiet?

Whether it's a flight overhead or the hum of an air conditioning unit, the busy world around us tends to make it hard to find silence. All of this residual sound is having more of an impact than you might think.

Last year, the U.S. Bureau of Transportation Statistics published a map depicting levels of aggregate noise throughout the country. As you might expect, it's louder in more populated areas, and quieter in areas with less population density.

However, the effect of noise in natural areas is still very measurable, and elevated levels have been shown to negatively impact the localized ecosystem.

A study published by Science Magazine found that 63 percent of protected natural areas around the country have man-made noise present at detrimental levels, capable of having an impact on nearby wildlife. For example, birds in these noise-heavy areas have become desensitized to additional noise, making them potentially less likely to flee in the presence of predators.

Noise has been shown to have the opposite effect on ground-dwelling rodents. Instead of becoming desensitized, they tend to become hyper-aware when extra noise is present, according to a study published by Oxford Academic. This learned behavior can cause them to go into hiding more frequently, especially in cases where they're found near roadways. As a result, they have less time to forage for food while they're expending additional energy hiding from every perceived threat.

In 2008, the European Heart Journal released a study that tracked humans living near airports, constantly exposed to the sound of planes taking off and landing. Researchers found that heart rates rose when humans were exposed to noise greater than 35 decibels. To put that in perspective, 35 decibels falls between a whisper and a light rainfall, with normal conversation falling at roughly 60 decibels and a running washing machine at 75 decibels.

By studying the Bureau of Transportation Statistics' national transportation noise map, it's clear that 97 percent of Americans experience noise at 50 decibels or higher on a regular basis, likely resulting in elevated stress levels with potential long-term effects. It's also likely that other animals inhabiting those areas are similarly affected.

But why does it matter?

Consider this scenario. A small prey animal is out on its normal morning stroll. Years ago, before noise pollution was as prominent as it is today, a listening range for that animal might have been 100 feet. Today, according to a study by a coalition of Colorado State University researchers and the National Park Service, that listening range is reduced by 90 percent in one in five natural areas around the country. That means that today, that same prey animal in an affected natural area might only be able to hear things happening at around 10 feet away.

This noise isn't just a nuisance; it acts as a distraction from food gathering and predator detection. The decrease in sustenance and limiting factor of the noise make it easier for the predators to catch their dinner. This advantage on behalf of the predator can result in an imbalance that throws off the proper predator to prey ratio in a given ecosystem. As prey populations dwindle, predators can be forced to find a new food source or starve, impacting an entire food chain in the process.

In the modern age of cars and planes, noise pollution won't be going anywhere anytime soon. However, we can do things in our everyday lives to reduce the instances of noise pollution in fragile ecosystems.

Consider how much noise you're making next time you're in a natural area. Do you really need a portable speaker for your hike? Think about the prey that's trying to hear a predator coming or the tree that needs birds around to spread their seeds. Small changes like turning your music off may seem incremental, but these small changes do actually limit the impact that this pollution can have on entire ecosystems.