Biologists from Boise State University have been making noise in the forests of the western American state of Idaho. They are making noise to study the value of quiet in nature. They want to know how people and animals react to noise pollution.

The researchers placed outdoor speakers on the side of a half-kilometer-long part of a road in the Boise National Forest. For two years, they played the sounds of passing cars through the speakers. Professor Jesse Barber of Boise State University says they found the sounds causedmigratory birds to flee. The birds also failed to gain weight.

This is one of six loudspeakers mimicking natural gas well field compressor noise at study sites on Idaho's Snake River Plain. (VOA/T. Banse)

Recently, researchers played sounds of machines that are used to remove natural gas from the ground.

That sound is heard in natural gas fields throughout the American West.

Professor Barber says these experiments are designed to help researchers learn the effects of noise pollution on birds, insects, bats, plants and people.

"We are testing the idea that these things are coupled -- that as the soundscape gets louder, wildlife suffers. But that also feeds back on to how much people get out of that experience, how much they value it, and thus how much they are willing to protect that same place."

The research team also studied a group of volunteers who watch birds for fun. Mitch Levenhagen is a graduate student in the research team. He measured how much the artificial noise lessened the ability of the birdwatchers to identify recorded bird songs.

He recorded eight songs in the noise condition and eight songs in the quiet.

He then repeated the experiment without the artificial noise. The birdwatchers were happy when the noise machine was shut off.

The birdwatchers said the artificial noise affected their ability to identify bird sounds more than they thought it would. Birdwatcher Jim Lyons said the experiment caused him to value quiet more.

"The whole thing has been ear-opening, shall we say. To be part of this is very stimulating, very interesting. I am going to think about it from now on."

Volunteer Janice Engle said she, too, likes the quiet.

"I moved out of the city to a little place in the country where I wanted it to be quiet. I greatly value that. It is hard to find those places more and more. There are lots of ways to mitigate sound. But it istrade-off. There is always a cost. And it comes down to people's values. What do we value more."

The National Park Service is paying for some noise pollution research. The federal agency is also examining other ways to reduce noise. They include putting new surfaces on roads. And they are creating quiet areas with signs telling visitors to turn off their mobile phones. Visit the website www.chinavoa.com to get more information!

Next year, Mr. Levenhagen and Professor Barber will go to Northern California to ask visitors at Muir Woods National Monument and other parks how they feel about noise.

I'm Jim Tedder.

Correspondent Tom Banse reported this story from Boise, Idaho. Christopher Jones-Cruise adapted it for VOA Learning English. Hai Do was the editor.

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Words in This Story

migratory – adj. moving from one place to another at different times of the year

couple(d)– v. to join (two things) together

wildlife– n. animals living in nature; wild animals

artificial – adj. not natural or real; made, produced or done to seem like something natural

stimulating– adj. exciting or interesting

mitigate– v. to make (something) less severe, harmful or painful

trade-off – n. something that you do not want but must accept in order to have something that you want; a situation in which you must choose between, or balance, two things that are opposite or cannot be had at the same time