BENTON, N.H. – The hiker trudged up a logging road and into a valley, tracing a route that seemed unremarkable. There were no sweeping views of mountains. There was no summit to scale. Yet he stopped suddenly, jubilant, after about 4 miles of walking. He had found exactly what he was searching for: quiet.

"Let's see," said Dennis Follensbee, "how we experience three minutes of silence."

In these loud times — with political foes yelling on television, trucks rumbling through streets and smartphones chirping all around — who doesn't want a little peace and quiet? But some wilderness lovers have taken their aversion to the cacophony of the modern world a step further, traveling to some of the country's most remote areas in a quest for utter silence.

Armed with Google Maps, bushwhacking tools and 16 years of experience hiking in the area, Follensbee, a programmer, is on an exhaustive search for the noiseless hollows and dells of New Hampshire's White Mountains.

"I know there must be places I can go to have peace," said Follensbee, 39, who has mapped 23 quiet places so far, although he has shared the exact locations only with family members and close friends. (If quiet places are widely known, he reasons, "they cease to be quiet.")

Connoisseurs of quiet say it is increasingly difficult, even in the wilderness, to escape the sounds of vehicles, airplanes, industries and voices.

A study published last year in the academic journal Science found that noise pollution was doubling sound levels in much of the nation's conserved land, such as national parks and areas preserved by the federal Bureau of Land Management.

Noise that humans create can be annoying but also dangerous to animals that rely on hearing to seek their prey and avoid predators. "We're really starting to understand the consequences of noise and the importance of natural sound," said Rachel Buxton, a conservation biologist at Colorado State University who worked on the study.

In Washington state, Gordon Hempton, an acoustic ecologist — part of a small field of experts who study natural soundscapes — has made it a mission to preserve what he calls "1 square inch" of quiet in Olympic National Park. He and other advocates have raised concerns about noise from loud Navy jets and other air traffic, but says he believes that Olympic National Park is one of only about 12 places in the continental United States where a person could listen for 15 minutes and hear no man-made sound.

"We need to defend quiet places that remain as well as clean up places that should be quiet," Hempton said.

Keeping things hush-hush

To some degree, those efforts are underway. The National Park Service has a policy requiring park managers to measure "baseline acoustic conditions" and determine which noises have an adverse effect. There is even a branch of the Park Service known as the Natural Sounds and Night Skies Division that is dedicated in part to preserving the untrammeled soundscape.

At Muir Woods National Monument, officials have posted signs urging people to keep their voices soft. Low-flying air tours are banned over Rocky Mountain National Park. In 2015, at Grand Teton National Park, officials installed a noise meter — similar to a roadside speedometer — that showed passing vehicles how much noise they are making. And this year, parks officials repaved a road in Death Valley with different kinds of surfaces so they could compare how much noise each one produced.

Efforts to regulate noise have never been as broad or well organized as some environmental causes, and they sometimes have lost steam or been met with opposition from industry groups. In the 1970s, the Environmental Protection Agency had an Office of Noise Abatement and Control, but it lost its funding during deregulation of the early 1980s.

For years, conservationists seeking to minimize noise from visitors and helicopter flights at the Grand Canyon have met opposition from businesses and Indian tribes that depend on tourism and recreation. And people whose passions make noise — such as snowmobilers and motorcyclists — argue that they, too, have the right to enjoy the wilderness.

Loud engines, crowds

On a recent Sunday afternoon, motorcycles thundered up the Mount Washington Auto Road, and cars lumbered around hairpin turns. At the top of the mountain, the wheels of a motor coach rumbled over the gravel, and the biodiesel engine of the Cog Railway, which carts visitors up and down the mountain, whirred constantly.

Hiker Richard Davy's journey up the mountain brought him to the summit, where the sound of a crying child could be heard over all else. He takes a semiannual pilgrimage here, and said he hoped his ashes would one day be scattered here. "With that crying kid, I don't know, I might reconsider," Davy, 69, said.

Given the loud crowds, some hikers have taken to avoiding the tallest mountains, making lists instead of quieter getaways. But even in out-of-the-way places, silence can be fleeting.

When Follensbee found one of his preferred spots the other day, he pulled out his phone to record sounds. He is not looking for a complete auditory vacuum, but a place without man-made noise where you can hear the sounds you can hear only when it is quiet.

For three minutes, a soft hum of insects, a rustle of leaves and the calls of birds was all there was. Then came the whine of a vehicle, its motor growing louder as it came over a ridge. It ruined everything.

"It is a little disappointing," Follensbee said, shaking his head. "We're so far out."