There's nothing like a beautiful sunset to soothe our nerves. Until, that is, a manmade noise like a car alarm or a plane's engine roars overhead.
According to the people who study bioacoustics — or natural sounds — it is becoming increasingly difficult to find undisturbed natural habitats.
When Bernie Krause first started recording nature sounds in 1968 for films and television, it took him 15 hours of recording time to glean one hour of pristine sound.
"Now it takes me 2,000 hours in North America to get one hour of usable material," says Krause.
Krause is worried about the effects of all that noise on the animals and their habitats.
He has coined the word "biophony" to describe the way creatures vocalize at different frequencies so they can communicate with their own kind.
Harmful to the Species' Survival
In a natural soundscape, manmade noise can be harmfully disruptive. For example, one community of frogs in a California lake is being affected because they can't communicate over the unnatural sounds, and then in turn, protect themselves.
"The reason that frogs all chorus together is because no predator can get a bead on anyone," says Krause. But when a jet plane flew overhead, the frog's unified chorus was broken. Krause says he then witnessed predators homing in on individual frogs.
"Great horned owls flew in and got frogs and coyotes got frogs," says Krause.
The lesson is clear, he says. Noise pollution can affect the very survival of a species.
Protecting Soundscapes Through Regulation
The National Park Service recently designated natural soundscapes a resource, which means they must be protected, like clean air or clean water.
The impact of noise on natural habitats is already being taken into consideration in places like San Francisco Bay, where the renovation of a major commuter bridge is taking place right next to rocks that serve as a critical roost for harbor seals.
"The levels of sound you're talking about when you get into levels of pile driving and rivet removal along the bridge," explains Emma Grigg, a biologist of the Harbor Seal Project. "Seals are gonna be able to hear that and pick up on that."
The state is making sure that the construction barges stay away from the seals at sensitive times, like giving birth, which is not something the construction crews would do voluntarily since they want to finish their jobs quickly.
The seals have already adapted to some human noise, such as the sound of traffic. And other animals have had to learn to cope as well. But for all creatures, humans included, there is a limit.
"We have to stop it," says Krause. "We have to quiet down America."