From echoing mausoleums and groaning icebergs to reverberating stalactites and humming sand dunes, the world is awash in majestic hymns. Some of the most glorious sounds are crafted by the marvels of human architecture, but many others are natural splendors, songs caroled by Mother Nature herself.

But what are the grandest sounds of them all? That's what acoustic engineer Trevor Cox wanted to find out. So he embarked on an incredible journey led not by his eyes, but by his ears, to discover the most compelling sounds on Earth: the sonic wonders of the world.

He catalogs his awe-inspiring around-the-world journey at his website,, and in a new book, "The Sound Book."

"They're places that you want to visit not for the more typical reason, that they've got beautiful views, but because they've got beautiful sounds," he said, according to the Smithsonian.

A few of the destinations Cox has identified are easy guesses. Take, for instance, the famous St. Paul's Cathedral in London, which houses a room called the Whispering Gallery. This echoing chamber is so flawlessly spherical that sounds whispered against one wall can be heard clear across the room against the opposite wall, and with near-perfect clarity.

Other destinations, though, are not so well-known. A Cold War-era spy listening station in Berlin, used by British and American spies to listen in on East German radio communications, operates in a fashion similar to the Whispering Gallery. Its walls, too, are spherical, creating an effect equal to (if not greater than) the one at St. Paul's. But the spy station has an additional fascinating effect: By making noise in the center of the room, bizarre distortions can be created from the sounds bouncing off all the walls in equal measure. You can listen to a clip of these distortions thanks to the Smithsonian here: 

Perhaps the most interesting sounds on the planet, though, are those that have a natural component. Cox's acoustic travels have led him as far afield as Iceland, where he encountered icebergs that groan and croak, and the Mojave Desert, where sand dunes hum eerily when small avalanches of sand cascade down their slopes. He has visited a specialized organ built into a cave in Virginia which harnesses the reverberations of stalactites, and he has meditated in an Egyptian canyon that might just be one of the quietest places on Earth.

Cox has also listened in on the vocalizations of living things. One of the most unusual voices in the animal kingdom, he says, belongs to the bearded seal. 

"The bearded seal produces incredibly complex vocalizations, with the long drawn out glissandos that trill and spiral down in frequency," Cox wrote.

You can listen to these alien-like vocalizations from the male seals here:

So which sounds are the best of the best? It's difficult to pick and choose. Cox's primary aim is just to inspire others to explore the world themselves, to travel with a new kind of tourism in mind: acoustic tourism.

You can view all of the places Cox has explored at his website, and even vote on which ones you think are the most wondrous.

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