Loud, Strange, and Weird: The Amazing Science of Sound

by guest blogger Annabelle Lopez

Let’s explore the weird world of sound. To celebrate this ever-present but poorly understood phenomenon, we’re inviting you to try your luck at this sound trivia quiz (provided by London Soundproofing):

Link to quiz: http://www.londonsoundproofing.co.uk/sound-quiz/

How did you do? Don’t worry if you struggled to get many of the questions right. The quiz is tough, and deliberately so. But hopefully, you found yourself saying, “Well that’s funny…” instead of feeling frustrated. That’s because the quiz’s actual function is to inspire wonder and open the door to the weird world of sound. From my own personal experience, this is the trick to get people learning without realising it. Because it inspires follow-up questions and healthy curiosity, learning without realising is a neat gateway to many of the challenging topics.

Now that the gate is open, let’s look at the questions in more detail:

Number 1: What caused the largest sound ever recorded?

What’s fascinating about this question is many people instinctively think of the Soviet mega-nuke, the ‘Tsar Bomba’. This nuclear weapon, the largest ever detonated, was so big and destructive that it was actually militarily useless. The bomb was deployed from a fighter plane, with a parachute to slow its descent over the detonation site. This gave the pilots barely a 50% chance of escaping the blast, despite them managing to fly 30 miles away from the site before the explosion.

But even nuclear weapons pale in volume compared to nature. The meteor that hit in Tunguska in Russia, 1908, wiped away over 770 sq miles of forest and exploded with an estimated 300 – 315db. This would put the impact at around a thousand times louder and more powerful than the atomic bombs dropped on Hiroshima, Japan, at the end of World War Two.

And then there is the energy unleashed from inside the Earth itself. The Krakatoa volcanic eruption of 1883 is pegged at being a little bit louder than the Tunguska event. The initial explosion could be heard more than 3,000 miles away, and the shock waves exploded the eardrums of anyone within 40 miles of the eruption.

Number 2: How fast does sound travel?

What’s fascinating about this question is that all of the answers refer to the speed of some property of the Universe. The first answer, 54 metres per second, is actually the estimated speed of dark matter. Scientists aren’t entirely sure what dark matter is yet, but it accounts for almost all of the mass in the Universe. So scientists are working hard to ‘discover’ it.

We see fireworks before we hear them. Public Domain

 

The correct answer to this question is an impressive 343 metres/s. A lot of people understandably mistake this incredible speed for the speed of light. But sound is much slower than the speed of light. A good example of how much quicker light is than sound can be observed on Fireworks night in the UK. The light from the fireworks’ explosion always appears much faster than the sound. Light travels at almost 300, 000, 000 m/s.

Light, of course, is the fastest known property in the Universe – but it isn’t the fastest property humans have observed. That incredible award goes to the Universe itself, which is expanding at approximately 67 kilometres/s per megaparsec. Nothing can travel faster than light, except for the Universe itself.

 

Number 3: What is the loudest animal on Earth?

Contrary to popular belief, the sperm whale is louder than the blue whale. Sperm whales caterwaul at around 230db – much louder than a jet engine at take off. Although many of the sounds it emits are not audible to the human ear, the combined Hz make it the loudest animal on Earth. The “screaming” pistol shrimp and the howler monkey are loud, but aren’t as loud as their names suggest. They are effectively trick answers to the question.

Number 4: What would be the minimum sound level required to kill a person?

This is my favourite question to ask, because all of the ‘answers’ are fascinating, no matter which one is picked.

Because sound operates on a logarithmic scale, 100db is actually 10 billion times more powerful than 0db. At 145db your vision would start to vibrate; at 165db your eardrums would rupture, and at 195db you would no longer have a sound wave but a shock wave. This would be enough to cause massive internal damage without any physical damage.

After air raids during World War 2, casualties with no wounds or any sorts of marks were reported. Upon autopsy, it was noticed that their internal organs were destroyed. That’s the power of a shock wave.

1,100db is the equivalent of 10^98 watts of power. A shock wave of this magnitude – even if it only lasted about 1/10th of a second – would produce the same amount of energy as 47 quinvigintillion tsar bombs (the mega nuke in question one, the largest nuclear bomb ever detonated). The energy would generate a black hole with an event horizon larger than the observable universe.

A quinvigintillion is a number is a 1 with 79 zeros after it.

Number 5: What animal sound(s) were used to create the velociraptor’s “bark” in the Jurassic Park movie?

All of the animals in this question were used to make the sounds of some of the dinosaurs in the Jurassic Park films, but the answer, incredibly, is two tortoises mating. Some of the tyrannosaur noises are actual recordings of a baby elephant snorting; and when a female horse is “excited” by a male, she can squeal quite aggressively. This” squeal” sounds almost bird-like, and was used as the cry of the gallimimus dinosaur. A walrus and fox combination was used (in addition to other things) to make the roar of the indominous rex – the big baddie in the Jurassic World sequel, released in 2015.

The sound of a T Rex or a baby elephant snorting?! Image CC 3.0 LadyOfHats

Number 6: Which of these is a side-effect of very low (infrasound) sound frequencies?

The trick answer is: tinnitus. A symptom of tinnitus is an ever-present soft humming or buzzing sound, but infrasounds are not audible to humans. But even though we can’t hear them, it doesn’t mean they can’t affect us. Infrasound waves are picked up by the body subconsciously. They can be ‘felt’ in the form of vibrations, chills running up the spine, a tight pressure on the chest and – incredibly – even as ghostly apparitions or hallucinations. Because of these manifestations, infrasound waves are said to operate on sound’s ‘fear frequency’.

Diarrhoea has also been reported as a symptom of even lower sound waves beyond infrasound. Dubbed the “brown note”, some sound frequencies between 5 – 9 Hz appeared to make astronauts lose control of their bowels during the early days of the US space programme. However, these claims have never since been substantiated.  

Number 7: Black holes are known to emit sound. But in what musical key?

Contrary to popular belief, some sounds do exist in space – it is just that we can’t hear them without extraordinarily advanced instruments. Perseus’ black hole oscillates every 10 million years, that’s sound on a massive scale, played across deep time. The Chandra X-ray telescope has detected these sound ‘ripples’ in the gas that fills the Perseus Cluster. Unfortunately the sound needs the gas as a medium to travel through, but just by looking at the patterns left in the gas – believed to be crests and troughs of sound waves – we can determine that the black hole is emitting notation in B-flat.

A ‘semibreve’ of course, isn’t even a note at all; it is the name for a whole note in general.

Question 8: What happens if you tap the Stonehenge rocks with a hammer?

There’s the sound of bells, drums, and gongs. For centuries, archaeologists have been baffled by the pagan decision to lump stones from South Wales to Wiltshire in order to build the Stonehenge monument – particularly as Wiltshire is home to many beautiful types of rocks.

But now they think they understand why. The ‘bluestone’ rocks of Stonehenge have a so-called “acoustic energy”, sounding like bells, drums, and gongs when struck. It has since been claimed that Stonehenge is the earliest known musical instrument, other than the voice and basic drums. There is a theory that Stonehenge may have sounded like a church tower to the masses from a distance, but this is only speculation.

Stonehenge, a musical monument! Public Domain

Question 9: How many deaf people, approximately, are there in the world?

Around 466 million people (5% of the global population) are estimated to have so-called ‘disabling hearing loss’ and most of it is a result of preventable causes. That’s more than the combined populations of the United States, the UK, Canada, and Poland. People most likely to suffer from disabling hearing loss are those over 65; especially in South Asia and sub-Saharan Africa. Most people don’t imagine the number to be so high.

Question 10: In how many films has the stock sound effect the ‘Wilhelm Scream’ featured in?

The answer is 389. You’ve almost certainly heard the Wilhelm scream before. This stock sound effect resembles that of a man screaming and has become a bit of a tradition among Foley artists. It has been used in Star Wars, the Simpsons, and Dunkirk.

Feeling ‘funny’ yet?

There’s an old saying about storytelling: that after a story is concluded, it’s not what the characters said, thought, or did that people remembered, but how the story made them feel. I believe a similar process is necessary to open the door to the more difficult subjects. When it comes to exploring the Weird World of Sound, we’ve barely scratched the surface. But if this quiz and article has succeeded even slightly, it’ll should be just the beginning of a lifetime of fascination and interest.

 

Posted in Physics