(CNN) — If you're one of the many people noticing the lilt of birdsong more profoundly these days (or perhaps even for the first time at all), you're not alone.
Everywhere from the Upper West Side to Wuhan, the phenomenon of all this suddenly more audible tweeting-in-the-wild is one of the commonly cited bright spots in the world right now.
And for one acoustic ecologist who has circled the globe three times researching and recording some of the world's most beautiful natural soundtracks, there's hope that when leisure travel enters our lives again, people might open their ears to sonic experiences while enjoying scenic ones, too.
"The longer we listen, the more we relax," says Gordon Hempton, co-founder of Quiet Parks International, an organization that aims to certify and preserve truly quiet spaces within reach of everyone on earth (including in urban areas).
Last year, the group awarded its first Quiet Wilderness Parks designation to the Zabalo River in Ecuador. And Taiwan's Yangmingshan National Park, in northern Taipei, will be officially announced as the first Urban Quiet Park and Quiet Trail during a ceremony on June 5. QPI plans to certify roughly 50 more parks throughout the world over the next decade, according to Hempton.
"We have a birthright to quiet," he says, "And we've gotten a teaser of it during this lockdown."
What makes for good listening?
Hempton says there is no place left on the planet that's entirely devoid of manmade sounds (flyover air traffic, a biggie, is omnipresent everywhere). But certain places offer the chance to tune into the true sounds of silence with minimal intrusions.
And silence, it turns out, isn't silent at all -- rather, it's the sound of nature without mankind's cacophony, says Hempton.
The gold standard for good listening in a world where it's impossible to escape manmade noise, he says, is a stretch of at least 15 minutes of uninterrupted, purely natural silence.
"I like to think of it as adventure listening, and the longer we listen the more we relax," says Hempton about the experience of perking your ears to nature's soundtrack in such diverse places as Cape Cod National Seashore and the Kalahari Desert.
"We evolved with eyelids, but not with earlids," he says, "Maybe we've been looking for something and not found it because we should have been listening all along."
Follow Hempton's lead and listen up for some of the planet's most captivating sounds of true silence.
Quiet Parks International awarded its first Quiet Wilderness Parks certification to Zabalo River
A rainforest rumba at Zabalo River Wilderness Quiet Park, Ecuador
Quiet Park International's first designated Wilderness Quiet Park lies deep in the Amazon rainforest in Ecuador -- a mysterious place where monkeys and macaws live alongside giant river otters, anacondas and jaguars.
Here, natural silence reigns, and the indigenous Cofán people guide visitors out into it during canoeing and trekking ecotours with the Cofán Survival Fund.
"This is my favorite place to witness dawn, beginning around 4 a.m., roughly two hours before sunrise," says Hempton. "The jungle nightscape begins to change with the chirping of insects -- including a six-inch-long grasshopper -- that sound like birds."
Listen to the ocean's drumming at Cape Cod
The ocean's drum at Cape Cod National Seashore, Massachusetts
The sandspun arm of Cape Cod is a historical American playground steeped in summer vacation lore. It's also home to a unique listening experience for those who take the time to tune their ears to what the shoreline has to say, says Hempton.
"I wasn't really expecting it would be relatively noise-free since it's so close to Boston," says Hempton about Marconi Beach, located within the 68-square-mile Cape Cod National Seashore. "If you get up early in the morning to listen, you'll have a real treat."
That's when you can watch the sun rise over the Atlantic Ocean to the soft pounding of waves breaking over sugary sand with very little intrusion -- if any -- from human sounds, says Hempton.
"Waves sound different whether they fall onto sand, cobblestone or a rocky shore," he says, explaining that waves advancing over younger, pebbly shores take on a different tone than those washing up on wide swaths of packed sand.
"All of our oceans are drums. And the sound of the waves on Marconi Beach is a nice, clean, soft pound," he says.
The crater of Haleakalā in Maui is naturally prone to quiet.
Ted Soqui/Corbis via Getty Images
The quietest place on earth in Haleakalā National Park, Maui, Hawaii
The crater of Haleakalā, the East Maui Volcano, is considered the quietest place on earth thanks to its extremely low incidence of any human-caused noise intrusions paired with prime natural conditions, according to Hempton.
"It's such a tall volcano, so any air traffic is already below the rim," he says of the 10,000-foot peak. "The volcanic ash and sand there are sound-absorbing and the cold and dry conditions that prevail in the crater are unfavorable to sound propagation. Everything is muted, compared to at sea level."
There's a hiking trail that leads into the crater itself. But catching sunrise on the crater's rim (accessible by road) offers another sonic experience, says Hempton, made unusual for what it lacks. "You don't hear any leaves rustling in the wind here," he says. "The wind has a remarkable feel as it passes over the sharp edges of the volcanic rock."
Hempton says listeners should also perk their ears to the call of the Hawaiian petrel, a seabird that nests up high where there are no predators.
At the moment, Hawaii officials are discouraging visitors from coming to the remote islands, but this sonic wonder will be here when state officials are ready to welcome tourists again.
Dry air in the Kalahari Desert makes it difficult for sound to carry.
Patricia Lanza/Getty Images
Distinctive songbird tunes in the Kalahari Desert, South Africa
As with the extreme low humidity in a volcanic crater, the dry air in the stretch of the Kalahari Desert that wends its way through typical bushlands in South Africa makes it difficult for sound to carry.
In the dry season here, leaves are sparse or absent from trees. "Rain, when it falls, evaporates before touching the desert soil," says Hempton, "It's that hot and dry."
But that doesn't stop songbirds from getting their messages across in a most melodious way.
"Listen for a sunrise chorus of birds that thrive in dry conditions and produce distinct songs -- very different from one another -- that can travel in dry atmospheres," says Hempton. Among them, you might hear the melodies of the red-eyed bulbul, crimson-breasted shrike and laughing dove.
Anytime of year is good for listening in Olympic National Park in Washington.
The hum of insect wings in Olympic National Park, Washington
"Any time you can hear the hum of insect wings you know it's quiet," says Hempton, who points to the buzz of yellow-faced bumblebees tending the salmon berry flowers in Olympic National Park as a classic spring and summer sound.
He calls the 1,442-square mile park -- which spans diverse ecosystems that include glaciated mountains and old growth forests on the Olympic Peninsula in Washington state -- the "listener's Yosemite."
And Olympic National Park is the most sonically diverse of all parks in the United States, according to Hempton, with Pacific chorus frogs and thrushes among those contributing to the layered melodies.
"Any time of year is good (for listening) here," he says, "but May is fabulous for frogs and bird song, and August brings the driest weather for backpacking."
Listen to the dawn chorus at Grasslands National Park.
A North American prairie waking up in Grasslands National Park, Saskatchewan, Canada
Considered the best example of a North American prairie, Grasslands National Park, just north of Montana in Canada's Saskatchewan province, is a wondrous, wide-open terrain of plains that ripple with grasses.
"The annual attendance here is only around 10,000 people (compared to numbers into the millions at other national parks)," says Hempton, which only amplifies the natural listening experience.
The prairie birds have adapted their songs to the challenge of communicating under windy conditions by using a combination of rapid frequency and amplitude modulations, says Hempton. He calls the dawn chorus in Grasslands National Park (best heard from May into summer and fall) one of the "most musical sunrise concerts in the world."
Tune in at sunrise to the clear cadence of meadowlarks -- as well as potentially much larger animals in the distance, too.
"You might hear coyotes howling or even a low, mysterious grunting sound as I did once," says Hempton. "It was a buffalo I heard from eight miles away."
Sinharaja Forest Reserve in Sri Lanka is an undisturbed swath of rainforest.
Sublime sounds to sleep to in Sri Lanka's Sinharaja Forest Reserve
A UNESCO designated Biosphere Reserve and World Heritage site, the Sinharaja Forest Reserve in the southern reaches of Sri Lanka is considered the last undisturbed swath of tropical primary rainforest in the country. It also happens to be Hempton's favorite place in the world to sleep.
"Remember, our ears still hear and our minds listen while we sleep -- that's why alarm clocks work," says Hempton. And the natural night sounds in Sinharaja "weave a complex tapestry of rhythms" with the calls of myriad insects and frogs, he says, many of which are endemic to the area.
More than half of all of Sri Lanka's mammals and butterflies -- among other species -- can be found within the dense forest of primarily endemic trees, so you might hear endemic cicadas, leaf-dwelling shrub frogs and orange-canthal shrub frogs among those adding to the symphony.
Yosemite National Park offers areas of layered natural sound.
Swoon to snowy crickets in Yosemite National Park, California
Half Dome. El Capitan. Bridal Veil Fall. There's so much to appreciate from a visual standpoint in Yosemite National Park, you'd be forgiven for not noticing many sounds beyond the clicking of camera shutters and murmurings of other awed humans. But Yosemite's natural soundtrack is a delight.
"Down in the valley of Yosemite you can expect it to be noisy," says Hempton. "John Muir even complained about the noisy tourists and their mules back in his day."
But as soon as you begin to hike along the John Muir Trail to Little Yosemite Valley, says Hempton, the soundscape changes.
In early autumn, along the trail between Little Yosemite Valley and Vernal Falls, listen for snowy tree crickets chirping to a backdrop of the thundering falls -- a magically layered effect ("If moonlight could be heard, it would sound like that," is how novelist Nathaniel Hawthorne described the crickets' calls).
The pale-white, tree-dwelling crickets have a neat trick up their wings, too -- their chirp rate can be used to estimate the temperature where they are (count the number of chirps you hear in 13 seconds, then add 40 to that to get the rough temperature in Fahrenheit).
"By early fall, the water has taken on more delicate tones," says Hempton of the waterfalls, explaining that each has its own voice. "John Muir referred to this as the 'choir.' And you can enjoy that priceless experience the same as it was in the 1800s when he was here."