Tag: sound

Posted in Science & Nature

The Loneliest Whale

Posted on by Jinavie

In 1989, an array of US Navy hydrophones (underwater microphones) in the North Pacific Ocean discovered a peculiar sound. It sounded very similar to a typical whale song, but there was a crucial difference. Most whales sing at about 10-40Hz, which is a very low frequency sound. However, this specific whale song played at 52Hz – significantly higher than other whale songs.

Bill Watkins was a scientist who became fascinated by this sound. He detected the same sound year after year for over a decade and recognised that it was coming from the same whale. It followed seasonal migration patterns and the song had definite, common features of whale songs. But this song was higher pitch than every other whale he compared it to.

This whale has since been called the “52-hertz whale”, also known as “the world’s loneliest whale”. There have been no other recordings of whale songs like it. There are many theories about what kind of whale it might be, with the leading theory being that it is a hybrid of a blue whale and a fin whale. Because hybrid animals (crossbreeds) have different body morphologies to the parent species, theoretically it could produce a unique sound.

Whales sing to communicate with each other. In the vast ocean, sight becomes easily obscured, but the low-pitched vocalisations of whales can carry on for hundreds of miles. This raises the question of whether the 52-hertz whale’s calls are heard by other whales, given that it is talking in a different frequency range. If they can’t, there is a chance that this whale is calling out into the void, only to be ignored by every other whale. It might have been swimming alone for decades, in search of a partner who can communicate with it.

In some ways, we are all somewhat like the 52-hertz whale. Because we are all unique individuals, even when we talk in the same language, we often misinterpret each other or fail to make a connection because we cannot understand their way of thinking. This is why when you meet someone who thinks on a similar frequency to you, it is a connection worth holding on to. There is no greater thrill than meeting another soul who you can say one thing to and they will understand ten things.

These are the kinds of relationships you should treasure, because for all you know, you may end up like the 52-hertz whale – drifting along the deep blue ocean, desperately calling out in hopes of hearing any kind of reply.

(Image source: https://kaanbagci.deviantart.com/art/52-hertz-whale-445744029)

Posted in History & Literature

The Devil’s Interval

Posted on by Jinavie

(See below NB for a simple guide to musical notes and tones)

In music, depending on what notes you use in a single chord, you can produce beautiful harmonies as the tones complement each other. The opposite of this is called dissonance and it results in a harsh, unpleasant sound. A famous example of this is a tritone – a chord made from two notes exactly three whole tones apart. In a standard C major diatonic scale (which doesn’t involve any flats or sharps), there is only one tritone per octave: F and B. But on the chromatic scale (all keys), any number of tritones are possible.

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Historically, the tritone has been the black sheep of music theory due to its dissonance crashing any harmony of a song and being difficult to sing. It sticks out like a sore thumb among the sea of beautiful harmonies that other tones make. The tritone was hated so much so that it was named diabolus in musica (“the devil in music”) or the devil’s interval since the Middle Ages, even being banned in the production of music prior to the Renaissance. To this day, the tritone is suggested as an “evil”, “scary” sound.

Over time, composers worked around the tritone until they realised that thanks to the connotations, the tritone was a useful way to express “evil” in a musical way. The cultural association was exploited freely in works such as Franz Liszt’s Dante Sonata, where the tritone is used to depict Hell. The association is found in modern music as well to produce an unsettling feeling, such as the opening notes of Jimi Hendrix’s Purple Haze. The tritone is a common feature of heavy metal bands such as Black Sabbath.

Even though these songs use the devil’s interval, they are not at all inferior to “normal” major scale music. They are still beautiful in their own, interesting way. Perhaps the notion of good and evil have no place in judging whether something is beautiful or not.

NB: Musical tones are noted using the alphabet: C, D, E, F, G, A and B, with a flat(b) to denote a semitone lower, or a sharp(#) to denote a semitone higher. This is easy to visualise on a piano keyboard, where a single tone interval involves a white key, a black key in between and another white key. The interval between a white key and a black key is a semitone.

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(Image: Portion of Hieronymus Bosch’s The Garden of Earthly Delights depicting musicians’ hell)

Posted in Science & Nature

Sonic Boom

Posted on by Jinavie

When something moves through the air, it pushes the air in front and creates a sound. This sound spreads as a wave at the speed of 340m/s (1225km/h). As the object moves, it makes a series of pressure waves, which is why the Doppler effect happens. These pressure waves look like rings that are squashed to the side the object is moving towards. As the object moves faster, the more compressed these rings become. When the object moves at the speed of sound (340m/s), the pressure waves all overlap as the object makes a pressure wave on the same place as where the last wave reached. This is the sound barrier.

At this point, there is so much overlap of the waves that a shockwave is formed. This shockwave – made of compressed air – travels at the speed of sound (Mach 1) and originates from the front tip of the object (e.g. nose of the plane). If the object moves any faster than the speed of sound, the new wave is made even before the old wave has propagated that far. The rings are now no longer in a nice concentric pattern, but instead form a shockwave cone. Sometimes this can be seen physically if there is enough condensation in the air to create a vapour cone. The sudden change of pressure from the shockwave creates a large booming sound, which we call a sonic boom (in fact, there are two booms due to the pressure difference at the tail too).

Sound, like other waves, is a form of energy. Hence, the shockwave formed by breaking the sound barrier can cause physical damage. If a fighter jet were to fly over a building at low altitude at supersonic speeds, it may cause windows to shatter and people’s eardrums to rupture. The shockwave creates a significant problem in aircraft design, for if a plane’s wingspan is wider than the width of the shockwave cone, its wings will snap off. This is why fighter jets and the Concorde have a characteristic sleek, triangular shape. The faster the plane travels, the narrower the shockwave cone becomes and the thinner the plane’s wingspan has to be.

Then what was the first manmade object to break the sound barrier? The answer is surprisingly old and simple – a bullwhip. The crack from a whip is actually a small sonic boom made by the tip of the whip travelling beyond the speed of sound.

Posted in Science & Nature

Silence Of The Trees

Posted on by Jinavie

A timeless philosophical question goes like this:

If a tree falls in a forest, does it make a sound?

This may sound absurd, but the question hangs on the definition of sound. Is sound the physical phenomenon of vibrating particles forming a soundwave, or is sound the sensory information that we perceive by converting said soundwave using our hearing system? If you accept the first definition, then yes, the falling of the tree will generate energy that pushes on the air particles around it, causing a soundwave that if someone were to hear it, would sound as a “thud”. But if you accept the second definition, then that tree would not have made a “sound” per se because no one was around to perceive the soundwave. Following this logic, a sound cannot exist without a recipient to hear it.

As simple as this may seem at face value, the riddle explores some deep philosophical and scientific issues.

The most obvious one has been discussed: the definition of sound. But then one must question what would happen if a tape recorder was running when the tree fell. Can a machine hear, even though it cannot “sense”? Is the sound we hear being played from the recorder the same as the sound that was originally made by the tree?

Following on from this thought, how do we know that the sound you hear is an accurate interpretation of the actual soundwave? It is common knowledge that the brain frequently modifies the senses to change what it sees and hears, as seen in various illusions. Furthermore, the brain can generate sensory information without any input, known as hallucinations. You assume that your hearing is flawless and accurate, but in your mind, it is almost impossible to know for sure that the sound you heard is “real”. Taking this further leads in to the massive debate of “what is real?” and “is reality real or is it a product of our mind?”.

A more fundamental question is this: if no one was around to hear the tree fall, does it matter if it made a sound? A pragmatic philosopher might say “no”, as whether the tree made a sound or not makes no difference to your life. However, a scientist may say “yes” as the tree did fall and a soundwave was generated. Whether a person was around to observe it is irrelevant as it does not change the fact that something real occurred. Then what effect does observation have on reality? How do we know that trees make the same sound when we are not around to hear it?

This is a crude dissection of the vast number of questions the riddle offers, but it shows how such a simple thought experiment can be an effective tool to engage your critical thinking. If you do not fully understand the philosophy discussed, at least you can take away the fact that you can use the excuse of “sound is only a perception, I did not hear you, therefore what you said did not happen” when someone tells you to do something.

Posted in Science & Nature

Thuder And Lightning

Posted on by Jinavie

The best or worst part (depending on your preference) about a dark and stormy night are the majestic flashes of lightning and booming thunder. Most people confuse the two terms, typically using “thunder” to describe both, but technically thunder is the sound produced by lightning, which is the flash of light. Lightning occurs when dense clouds become electrically charged due to the collision of water molecules. As charge builds up, the cloud becomes negatively charged. The negative charge becomes so intense that it begins to push electrons towards the surface of the Earth, creating a positive charge. Electricity always flows from a negative charge to a positive charge through a medium. The intensity of charges causes the air to become ionized (plasma), making it suddenly conductive and allowing the electricity to flow from the cloud to the ground. This is seen as a flash of intense light. As the electricity travels through this channel of air, it superheats the air and causes a massive expansion of air, much like an explosion. This creates an intense shockwave burst, producing a sound that we call thunder.

Lightning is a deadly force of nature. It clocks a peak voltage of somewhere between 30 million to billions of volts – far exceeding the electricity that can be generated by humans. When a lightning bolt strikes a human, it has a mortality rate of between 10~30%. The two effects of lightning on the human body is electrical shock and heat. As lightning flashes over the skin to reach the ground, it leaves a striking pattern known as Lichtenberg figures (see below), showing the path of the electrical breakdown. The intense electrical burst can cause loss of consciousness, arrhythmia or sudden cardiac arrest. The heat generated by the electricity can cause severe burns both externally and internally. It can literally fry internal organs causing permanent damage to the heart, lungs and brain. Neurological symptoms such as amnesia, confusion, sleep disturbance and chronic pain have also been reported. Strangely, there are also reported cases of lightning curing ailments such as blindness, deafness and baldness.

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Because lightning is light and thunder is sound, one can calculate how far away lightning struck using the time between the lightning flash and the sound of thunder. Sound travels at 340m/s, so by multiplying the number of seconds between the lightning and thunder by 340, you can deduce the distance in metres. For example, if you see a lightning strike and then hear thunder after 7 seconds, the lightning must have struck 340m x 7s = 2380m = 2.38km away.

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Posted in Science & Nature

Doppler Effect

Posted on by Jinavie

Have you ever noticed that when a car or train speed past you, the sound it makes changes in pitch depending on where it is? For example, imagine a train loaded with a marching band. You watch the train come closer and closer to the station where you wait, while the band plays a single note. As the train approaches, the pitch of the note gets higher and higher. The train does not see you and races past the station. As it gets further from you, the note played by the band becomes lower and lower in pitch again. If you cannot imagine this, the next time you see a police car or ambulance racing past you, carefully listen to the sound of the siren.

This change in pitch is called the Doppler effect. The Doppler effect is defined as the change in frequency of a wave (such as sound) for an observer moving relative to the source. It occurs because of the nature of waves. When the source of the sound is still, sound waves ripple out in all directions at a uniform speed. But when the source begins to move, the waves in front of the source begins to bunch up as the source moves with the wave, shortening the distance between each successive wave. As the waves bunch up, the frequency of the sound wave increases, causing a stationary observer to hear it as a higher pitch. This is essentially the same as the waves in the front of a moving boat being bunched up.

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The Doppler effect is very useful as it lets the observer measure the speed of the moving object from the amount of “shift” that occurred in the measured wave. This is how speed guns work. Astronomists can use the shift in colour of a star to measure the speed at which it is moving away from or towards us (known as a blue or red shift respectively). In medicine, the Doppler effect is used to visualise the flow of blood in the heart or through vessels on an ultrasound.

In modern society, life gets extremely busy and we have to move quite fast to catch up with it. But like with the Doppler effect, sometimes moving too fast can distort things. You might lose track of what your hopes, dreams and priorities are. People might see a distorted version of who you really are and say that you have “changed”. So no matter how busy you are and how fast the world spins on, remember that it is okay to slow down every now and then just to get a clear picture of where you are, who you are or what you are doing. For in the wise words of Ferris Bueller: “Life moves pretty fast. If you don’t stop and look around once in a while, you could miss it”.

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Posted in History & Literature

Silence

Posted on by Jinavie

“Listen to the sound of silence.” ~ Buddhist saying

The anechoic chamber at Orfield Labs in Minneapolis is the quietest room in the world. It records a staggering sound level of -9.4 decibels (humans can only detect sound levels above 0dB), thanks to its special walls, floor and ceiling design that absorbs all sound instead of echoing it. The room is so quiet that the only sound you will hear inside is the sound of your own organs: the sound of air drifting in and out of your lungs, the blood being thumped out of your heart, the digested food gurgling in your stomach… Even your ears generate a tiny amount of noise from the tiny blood vessels in its walls. The absolute silence is so disturbing that the longest anyone has ever spent alone in the room is merely 45 minutes.

The disturbing power of silence is also demonstrated in the infamous musical piece 4’33” (4 minutes 33 seconds) by John Cage. When it was first premiered in 1952, the audience watched in anticipation as the pianist David Tudor entered the stage. Tudor calmly approached the piano and sat down with a graceful demeanour. Then, he closed the piano lid. For 4 minutes and 33 seconds, the pianist did not play a single note. His only actions were opening and closing the lid to mark the end of one movement and the start of the next one. After the 4 minutes and 33 seconds, he stood up, bowed to the (stunned) audience and exited.

The audience was confused, bewildered and angry. How dare they be mocked with such an outrageous performance? By definition, silence is the absence of music, meaning that the audience were not given the musical performance they expected. However, the audience simply did not understand the “sound of silence”. Outside of the anechoic chamber mentioned above, there is no such thing as absolute silence on Earth. For example, that concert room would have been filled with the noise of the unsettled audience shifting in their seats, the raindrops pattering on the roof and the sound of the footsteps of those who walked out in rage.

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Posted in Science & Nature

Belling The Cat

Posted on by Jinavie

There once lived a community of mice in the attic of a house. The mice would sneak into kitchens, gnaw holes in the walls and run about freely. The owners were so fed up that they brought in a cat, causing the mice to all hide in fear. The terrified mice eventually held a meeting to discuss how they would sneak around the house without getting caught by the cat. One mouse suggested: “What if we put a bell around the neck of the cat? Then we can hear it coming and run away.”. The mice unanimously agreed that it was a brilliant idea. However, when they came to decide who would bell the cat, no mouse was brave enough to step forward and the plan was never carried out.

What would actually happen if a cat was belled? Without a doubt, the cat would take it as a cruel, cruel punishment. Not because it cannot catch mice, but because the sound of the bell ringing every time it moves will be extremely loud for the cat. A cat’s hearing is six times better than a human’s. With this excellent hearing, the constant sound of bells attacking its eardrums would be physical torture for the cat.

Furthermore, a cat can hear frequencies as high as 40,000Hz. A person can only hear up to 20,000Hz, meaning a cat hears over twice the range of sounds we can. This combined with the boosted volume results in the cat living in a very noisy world. Ergo, putting a bell around a cat’s neck is an extremely atrocious thing to do.

Posted in Science & Nature

Chalkboard

Posted on by Jinavie

The sound of fingernails scratching a chalkboard is one of the most difficult sounds to listen to. This “screech” sound gives the sensation of your soul being ripped to shreds and invokes great discomfort. Why is this?

Professor Randolph Blake of Vanderbilt Center, USA, observed that this sound is very similar to the scream chimpanzees and macaque monkeys make when they see a predator. According to other researches on this phenomenon, many species of monkeys also hate this sound greatly. Blake used these facts to hypothesise that as our primitive ancestors used this sound to alert an enemy approaching, it has been programmed into our primitive brain to trigger a negative response. Also, physically this sound amplifies in our ears at a certain frequency to cause intense pain. The pain and our basic instincts combine to generate such an unpleasant feeling.

Posted in Science & Nature

Resonance

Posted on by Jinavie

The power of vibration is incredible. Vibration allows a microwave to heat food and causes cities to be destroyed by earthquakes. The most interesting feature of vibrations is resonance, where a vibration of certain frequency greatly amplifies the vibration of another object. Every object has a natural oscillating frequency and when another wave of the same frequency hits the object, the oscillation suddenly amplifies and resonance occurs.

The best example for resonance is a swing. If you push a person on a swing at the same frequency as the swing’s natural frequency, you can achieve a much greater height than from pushing at any other frequency. Resonance can also be used to shatter a glass with only sound, by singing a sustained note at the same frequency as the glass’ natural frequency.

Resonance is how two things combine to create an even greater force.

1 + 1 = 3

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