What did the Big Bang sound like? Or Chicxulub? Tour the astonishing sonic landscapes of our world - Hindustan Times
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What did the Big Bang sound like? Or Chicxulub? Tour the astonishing sonic landscapes of our world

ByAnesha George
Apr 12, 2024 04:59 PM IST

A Book of Noises journeys back, and peers into the future. See how sound shaped the era of the dinosaurs, and how it’s altering medicine today.

Listening deeply is so important, in a time when more sounds are being destroyed than are being created, says Caspar Henderson.

(HT Illustration: Rahul Krishnan) PREMIUM
(HT Illustration: Rahul Krishnan)

“As we live through what many scientists describe as a mass-extinction event, more forms of life are dying out and the sounds they create are being lost with them.”

As a science journalist, a naturalist and an amateur musician, it was a combination of worry, wonder and curiosity that led him to take what he calls an “earwitness exploration of sound”.

After two-and-a-half years of exhaustive research, field work and compilation, A Book of Noises: Notes on the Auraculous was published, in 2023, by Granta and University of Chicago Press.

The book seeks to capture the ancient history of sound on Earth, and the astonishing breath of sonic landscapes in our world today. It touches upon sounds we haven’t heard but that have been pivotal to our existence — like the chimes that reverberated after the Big Bang.

It tracks how new developments in the study of sound are aiding doctors, ecologists, seismologists, and glaciologists struggling to predict what may happen next in Antarctica.

Sound has played an integral role in health care since the invention of the stethoscope in the early 19th century, Henderson, 60, points out. Medical ultrasounds, where high-frequency sound waves are used to map internal organs, and echocardiograms for the heart, followed soon after. Experimental physicists are now studying how neurons vibrate when they pass electrochemical signals, to try to frame non-invasive treatments for neurological disorders.

“Our first glimpse of the greatest wonder and trial of our lives, parenthood, comes in the form of a fuzzy black and white smudge made from sound,” he writes.

Sound is integral, in many ways, to life, he adds. In the evolving field of soil eco-acoustics, biologists are using sensors attached to metal nails pushed into the ground as a sort of antennae that allows them to “listen” to the movements of worms, grubs, mites and other life forms. Plant roots make a noise as they push through the soil too, and by tracking these, soil acousticians hope to better understand, for instance, whether roots grow by day, by night, or only after the rain.

“There are numerous scientific and environmental reasons to study sound. For me, it enriches my sense of what it is to be alive,” Henderson says. Take a tour of the soundscapes he uncovers, from the very first bang that brought about the universe.

The first sounds

For the first 200,000 to 300,000 years after the Big Bang, the rapidly expanding universe reverberated as if filled with countless booming cosmic bells, writes Henderson. The universe in these first million years was so dense that it trapped light but allowed sound to pass through it at a much higher speed than it does through the atmosphere on Earth today.

These acoustic waves weren’t really chimes, he explains, but they did help shape the distribution of matter, with the wave peaks becoming foci for matter that would evolve, over millions of years more, into galaxies.

The sound of the Big Bang itself was first simulated in 2003 by John Cramer, then a researcher at the University of Washington. It likely would have been less of a bang and more of a low-frequency hum, he found. It would have been inaudible to human ears.

Data on the early wave peaks, meanwhile, is drawn from the findings of an international consortium of scientists working with the Dark Energy Spectroscopic Instrument (DESI), which sits in the Arizona desert and was built as part of an international effort (by countries including the US, UK, France, Mexico and Spain). The scientists have, over about five years, been studying the positions and velocities of millions of galaxies across 11 billion years of cosmic history.

The earliest chirps

Among the earliest notes intentionally sounded on Earth were the cries of the katydid, a kind of cricket, which rubbed a serrated vein on one wing against a plectrum on the other in an early example of stridulation.

This would have first occurred about 165 million years ago. The exact pitch – at 6,400 Hz, about a fifth above the highest note on the piano – can be deduced from the anatomy of remains preserved in amber.

In a recreation published in 2012, this stridulation sounds tinny and electronic: like a very small fire alarm running out of batteries, says Henderson. (These are among the first notes, or pitches, that palaeontologists can accurately reconstruct, and are not necessarily the earliest notes or songs of creatures on Earth.)

Ancient animal noises

The earliest animal sounds to have been accurately reconstructed are that of the Parasaurolophus, a plant-eating hadrosaur or duck-billed dinosaur, roughly the size of a bus, that lived in North America, about 75 million years ago.

The Parasaurolophus’s call was probably made through a hollow bony tube on its head. In the 1990s, scientists at Sandia National Laboratories in New Mexico created a full-sized replica, and discovered that it made a “splendid” noise.

Pitched at about 30 Hz, or just below the bottom note of a piano, the timbre has been compared to that of a trombone, because of which the Parasaurolophus is also called the trombone dinosaur.

It turns out that large carnivorous dinosaurs such as the Tyrannosaurus rex, meanwhile, did not roar at all. Palaeontologists have concluded that they probably boomed, closed-mouthed, like a crocodile, at the lower end of human hearing and into the infrasonic range, with perhaps some groaning and hisses thrown in.

(The T-rex bellows in Jurassic Park? Those were created using a mix of slowed-down baby-elephant cries, the roar of a tiger, some whale song, an alligator hiss, and the bark of the sound engineer’s pet dog.)

The birth of birdsong

The earliest bird that definitely made a noise was the Vegavis iaai, which lived in Antarctica about 67 million years ago. Fossils show the presence of a syrinx, the avian equivalent of the larynx or “voice box” in humans, in its windpipe, just above the lungs. This indicates that it was able to quack or honk.

Birdsong began to rapidly evolve from those quacks and honks, about 30 million years ago, when Australian plants adapted to their steadily drying climates by excreting the sugars they produced, as nectar or plant sap. Australian birds quickly evolved to tap into these new resources: they began to taste and seek out sweetness, grew larger, more aggressive, cleverer and, they became vocal.

The loudest boom

The loudest sound ever produced on Earth was probably the shrieking, hissing crash of the Chicxulub impactor, as it struck present-day Mexico 66 million years ago, wiping out most of the planet’s non-avian dinosaurs (among numerous other species) and sending shock waves over land and sea.

Chicxulub was an asteroid larger than Mount Everest, and it struck Earth at 20 times the speed of a bullet. It drove itself so far into the Earth, that in moments, the rim of the 100-km-wide crater was made up of peaks higher than the Himalayas are today; they soon collapsed amid the chaos.

The sound of the Chicxulub crash would have been at least 500,000 times louder than what is perhaps the loudest sound in human history: that of the 1883 eruption of the Krakatoa volcano. This explosion sent pressure waves rippling around the Earth. It pushed a tsunami 45 metres high on to the shores of nearby Java and Sumatra, killing an estimated 120,000 people.

The captain of the Norham Castle, a ship stationed 64 km from Krakatoa, wrote that the explosions burst the eardrums of over half his crew. More than 160 km away, the sound was measured at about 172 dB, over eight times the threshold for pain in humans, and about four times as loud as a jet engine if one were standing right next to it.

Notes in space

While the Northern Lights or aurora borealis do not in themselves make any noise, in the right conditions, they can give rise to electrical discharges 100 metres or so above the ground that sound like gentle crackles and bangs. These sounds have been described by indigenous peoples and travellers in the Arctic for centuries, and were first recorded by scientists in the early Aughts.

Seismometers placed on Earth’s moon enable researchers to measure shudders and groans caused by meteor impacts. These are measured as vibrations within moon rock, since the moon itself is an utterly silent place. Sound needs a medium to travel through, and without a significant atmosphere, it cannot travel there.

The atmosphere on the surface of Mars, meanwhile, is about 100 times less dense than on Earth. The cold air, which is primarily carbon dioxide, would reduce the speed of sound, which would serve to lower the pitch of the human voice. But the thin atmosphere would raise the pitch, by about as much. So, though the waves would travel slower, humans would sound pretty much the same on Mars as they do here on Earth.

The oldest surviving musical instrument

Unearthed in a cave in south-eastern Germany, the oldest surviving purpose-built musical instrument is a flute made from the radius bone of a vulture, about 42,000 years ago. It has five holes bored along its length and a V-shaped notch or blowhole on the end. Replicas made in recent years sound a pentatonic or five-note scale.

The oldest-known complete musical composition

Inscribed in Greek 2,000 years ago on a tombstone near Ephesus in Turkey is the oldest-known complete musical composition. The notes and rhythm are indicated through accent marks that made the rhythm quite easy to recreate. What emerges is a light, almost danceable melody, Henderson says, which suits the lyrics:

While you live, shine

have no grief at all

life exists only for a short

while

and time demands his due

Acoustic terror

Sound can kill. At above 185 decibels, it can cause an air embolism in the lungs that then travels to the heart. Noise at this intensity has the potential to be used as a physical weapon, though so far, the bombardment of noise (specifically certain kinds of music) has tended to be been used, in military operations, as a psychological weapon instead.

Acoustic comfort

Speaking of the heart, Japan has a Wind Phone or Kaze no Denwa that people can talk into, to leave messages for loved ones they have lost. The phone is simply a disconnected old receiver, that sits atop a hill. But thousands have travelled to it, every year since the Tohoku tsunami in 2011.

It was set up by landscape designer Itaru Sasaki at the bottom of his garden, after being overcome with grief at losing his cousin to cancer in 2010. “Because my thoughts couldn’t be relayed over a regular phone line,” Sasaki told the Japanese TV channel NHK Sendai, “I wanted them to be carried on the wind.”

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