7 SONIC WONDERS OF THE WORLD
Our ears play an immensely important role in how we perceive our surroundings. Yet sound is often overlooked in our visually dominated world. Many lists of Seven Wonders have been compiled over the years, but they have ignored our sense of hearing. To redress the balance, I have travelled the world to hunt for our planet’s most remarkable and exotic sounds.
1 Musical Road, California
Just outside the city of Lancaster in California is a Musical Road – when you drive along it, you hear the frantic gallop from Rossini’s William Tell Overture. The melody is created via wheel vibrations, caused by different spacing between the corrugations in the road. Where the corrugations are close together you get a high note; when they are further apart, you get a lower one. This is Lancaster’s second Musical Road. The first was built for use in a car commercial, but had to be moved because nearby residents complained that the noise woke them up.
2 The Imam Mosque, Iran
Constructed in the 17th century, this mosque in Isfahan, Iran, is visually stunning, with dazzling blue ceramic tiles. But it creates some audible delights, too. A huge dome rises above the floor and tour guides delight in standing underneath it and snapping or flicking a piece of paper to create a short, sharp sound.
The room immediately responds with quick-fire echoes, ‘clack, clack, clack’ – about seven of them, in fact. Sound bounces back and forth between the fl oor and ceiling, with the curved dome focusing it and keeping it moving vertically up and down in a regimented fashion.
Without a dome, the echo from the ceiling would be lost among all the other sound reflections in the mosque.
3 Singing sand dunes, California
There are 40 dunes in the world where a small avalanche can cause the sand to emit a loud, deep hum. One of these is among the Kelso Dunes in the Mojave Desert, California. Find the right slope, and as you climb up the dune the sand will honk and sound like a badly played tuba. Scoot down on your backside to create an avalanche, and the whole surface will vibrate, creating a sound like the drone of a taxiing aircraft at an airport. This is a rare phenomenon because the sand grains must be just the right shape and size, and very dry, to create a musical note as they slide past each other.
4 The world’s longest echo, Scotland
The Inchindown oil tanks were dug into a hillside north of Invergordon in Ross-shire, Scotland. They were built to protect the Royal Navy’s fuel supplies from German longrange bombers during the Second World War. Each concrete tank is twice the length of a football pitch, with a high, arched roof. There are no doors to get into the tanks; visitors must be pushed through oil pipes to get inside. But if you were to play a single note on a trombone inside, the sound would reverberate for nearly two minutes after you stopped playing.
A new Guinness World Record was measured here, using the bang of a starting pistol. Acoustic scientists proved that a gunshot resonates for a full 75 seconds in the tanks, extending the world record by a whole minute.
5 Song of the bearded seal, Arctic Ocean
To hear this sound you need to drop a hydrophone (underwater microphone) through a hole in the Arctic ice to pick up the calls of bearded seals in the water below. The seals create long, drawn out glissandos that trill and spiral down in frequency. They sound more like UFOs coming in to land than any animal noise.
As seals create this call, they dive downwards in a spiral, releasing bubbles, before surfacing in the centre of their ice hole. This vocal athleticism probably evolved because females judge the fitness of the singing males by the quality of their song. Evolutionary pressure has driven the males to sing with ever more outlandish effects, including spiralling glissandos of extraordinary length.
6. Anechoic chamber, Salford
Anechoic chambers, such as the one at the University of Salford, Manchester, where I work, are incredibly quiet rooms found in acoustic laboratories. They are so quiet that no sound enters your ear canals, and all you hear is sound created by your own body. You might hear blood moving through your head and/or a high-pitched hissing originating in the auditory nerve. But the extraordinary quiet isn’t the main reason why some visitors ask to leave the chamber. There are no sound reflections from the walls, floor and ceiling because they are all covered in foam wedges. You can see the walls, you just can’t hear them, and some visitors find the disjoint between the visual and aural unsettling. One scientific study showed that if you turn the lights out, some visitors will soon start to have hallucinations.
7 Great Stalacpipe Organ, Virginia
In Luray Caverns, Virginia, among cave formations, sits a keyboard from a church organ. When a key is pressed, somewhere in the cavern a small rubber plunger taps a stalactite, which rings and makes an ethereal note. With each key connected to a diff erent cave formation, the organ can play 37 different notes.
The Great Stalacpipe Organ was the brainchild of Leland W Sprinkle. While visiting the cavern, Sprinkle heard a tour guide hit a cave formation with a rubber hammer, and he was inspired to make this unique instrument. He then spent three years armed with a small hammer, a tuning fork and an angle grinder, searching for good cave stalactites and cutting each one down to the right size for the note he sought.
Trevor Cox is professor of Acoustic Engineering at the University of Salford. His book, Sonic Wonderland: A Scientific Odyssey Of Sound, published by Bodley Head, costs £20.
1 Musical Road, California
2 The Imam Mosque, Iran
The room immediately responds with quick-fire echoes, ‘clack, clack, clack’ – about seven of them, in fact. Sound bounces back and forth between the fl oor and ceiling, with the curved dome focusing it and keeping it moving vertically up and down in a regimented fashion.
Without a dome, the echo from the ceiling would be lost among all the other sound reflections in the mosque.
3 Singing sand dunes, California
4 The world’s longest echo, Scotland
A new Guinness World Record was measured here, using the bang of a starting pistol. Acoustic scientists proved that a gunshot resonates for a full 75 seconds in the tanks, extending the world record by a whole minute.
5 Song of the bearded seal, Arctic Ocean
As seals create this call, they dive downwards in a spiral, releasing bubbles, before surfacing in the centre of their ice hole. This vocal athleticism probably evolved because females judge the fitness of the singing males by the quality of their song. Evolutionary pressure has driven the males to sing with ever more outlandish effects, including spiralling glissandos of extraordinary length.
6. Anechoic chamber, Salford
7 Great Stalacpipe Organ, Virginia
The Great Stalacpipe Organ was the brainchild of Leland W Sprinkle. While visiting the cavern, Sprinkle heard a tour guide hit a cave formation with a rubber hammer, and he was inspired to make this unique instrument. He then spent three years armed with a small hammer, a tuning fork and an angle grinder, searching for good cave stalactites and cutting each one down to the right size for the note he sought.
Trevor Cox is professor of Acoustic Engineering at the University of Salford. His book, Sonic Wonderland: A Scientific Odyssey Of Sound, published by Bodley Head, costs £20.