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Sound Energy | A Beginner's Guide Fans Listening to Music image

Sound Energy: What It Is and Why It Matters to You?

by | Educational, Energy, Science and Technology

The “Sound of Silence,” “Sound and Vision,” and musical hills alive with the sound of music — yes, sound is all around us in songs and our daily lives. 

But what exactly is sound, and more specifically, what is sound energy? Is there sound if no one hears it? (OK, we’re getting a bit philosophical here, but you can see how it leads to so many  more questions.) 

Almost all of us enjoy certain sounds that come across a broad spectrum, whether it’s the Beatles singing about a blackbird or the ASMR craze from quiet noises. Meanwhile, some workers need protection from sound energy and wear ear protection — from helicopter pilots to oil rig workers using heavy machinery.  

Let’s look at sound energy definitions and how our understanding of sound sources help shape our world. 

What Is the Definition of Sound Energy? 

Before defining sound energy, we need to understand two principal types of energy in the universe: 

  • Potential energy, or energy that is stored somewhere 
  • Kinetic energy, the energy of motion 

These energies can be subdivided into other forms of energy. Still, potential and kinetic energy remain the pillars of energy understanding. Take a look at our guide on potential and kinetic energy for deeper insight into these energies. 

Sound energy is one of these energy subdivisions. A sound wave is a form of mechanical energy. Sound energy is the energy released by an object’s vibrations — sound is what you get from vibrations. Sound travels as sound waves, which are vibrating particles. And sound waves can travel through gas, liquids, and solids.  

How Is Sound Energy Produced? 

Let’s take a bongo drum, and place it on the floor, ready to be played. It has potential energy in this position. Now, let’s hit the drum skin with our hands. That hand movement is kinetic energy.  

When your hand (kinetic energy) hits the bongo (potential energy), the bongo’s drum head and skin vibrate, causing its surrounding air molecules to vibrate. They vibrate against any nearby air molecules nearby, too, setting off a vibration chain reaction. The vibrating air molecules vibrate against neighboring particles, then the next set of molecules, and so on, creating a sound wave that travels outward from its source. 

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These vibrating molecules, or particles, which come from a vibrating object, make up a sound wave. For example, it’s easy to hear someone’s voice if you talk face-to-face with a few inches in between — the sound wave travels towards each person. If you double the distance and turn your backs to each other, it will be harder to hear each other’s spoken voices. The sound waves are traveling away from both people. 

Sound waves move when an object vibrates; this is called propagation. 

Sound waves, vibrating the air molecules around us, are detected by the human ear, causing the eardrum to vibrate. The bigger the sound vibrations, the louder the sound — this is known as its sound intensity. The intensity is determined by how strongly the air particles vibrate and shows how much energy there is in a sound wave. 

To imagine what a sound wave looks like, think of a Slinky wave made with one of those coily toys from your childhood. If you move the Slinky up and down or left and right from one end, you create a continuous wave that travels along the Slinky. The same happens with sound — the vibrations travel outwards as waves, heading in the same direction. 

The human body can create many different sounds to help explain the phenomenon. You could clap your hands, sing, crack your knuckles, or even swallow some water. All of these actions produce different types of sounds, and hence, sound waves. 

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Does Sound Have Energy? 

Yes, sound has energy. The waves of vibration are the energy of sound. 

How Can We Hear Sound Energy and Sound Waves? 

Sound Energy and Sound Waves | Man with Record Playersource

Sound waves travel through the air, or liquids, or solids, and arrive at our ears. The waves travel into our ear canals and then carry on to our eardrums and make our ossicles — three tiny bones in our ears — vibrate.  

From here, our now vibrating ossicles transfer the sound waves to our cochlea. At this point, so-called hair cells convert all those waves into signals our brain can understand and interpret, or “hear,” what we understand as sound. 

Think about listening to music. Let’s play the same piece of music three times but in different conditions. The first time, listen to it while standing in the same room as the stereo. The song should be clear as it travels through air. The second time, run a bath (enjoy!) and listen to the music while keeping your head and ears underwater. The sound changes because sound waves travel faster underwater. And finally, listen to the music in an adjacent room, with all the doors shut.  

The same piece of music will sound different in each environment because sound waves travel through each element (air, water, walls) in different ways. 

How Loud Is Sound? 

Sound waves alter depending on the sound’s loudness. The bigger the vibrations, the louder the sound, and the greater the amount of energy in the sound wave. 

If we lightly tap our bongo drum, it makes fewer vibrations — and little noise — than if we bash the drum with a wooden spoon with all our might. 

The greater the vibrations, the greater the sound wave’s amplitude. The amplitude is the height of the sound wave. A deafening sound makes a huge sound wave with a high amplitude, whereas quieter sounds have smaller sound waves.  

Both loudness and pitch affect the human ear. Excessive sound energy — which has enormous sound waves — can cause us severe pain and harm us, and in extreme cases, make us deaf. 

Why Do Sounds Have Different Pitches? 

As we’ve seen, a sound wave’s noise is determined by its height: the higher the wave, the louder the sound. A sound wave is also characterized by its length or the space between each wave’s peak. Think of the distance between regular waves that lap against the shore. 

Sound waves with peaks very close together produce higher pitch sounds. That’s because they are vibrating very quickly. Musical instruments like trumpets have high-pitched sounds and create sound waves that are close together.  

Conversely, sound waves with wave peaks further apart produce lower pitch sounds. These sound waves are vibrating more slowly. An oboe or bassoon are musical instruments with lower pitch. 

A xylophone illustrates this pitch difference perfectly. The lower, heavier, and larger bars produce a slower sound wave with greater distance between them than the higher pitch of the smaller, lighter bars. 

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Tuning forks come in different pitches and sizes. The smaller the tuning fork, the higher its pitch (assuming all materials used are the same), and the larger the tuning fork, the lower its pitch. If you hit the same tuning fork twice, once softly and once with force, the harder struck attempt will resonate louder because it has more sound energy. 

If a sound’s pitch is too high for the human ear, we call it ultrasonic. If it’s too low, we call it infrasonic.  

Architects and sound engineers study sound travel, called acoustics, when designing concert halls, cinemas, and anywhere sound is essential. Hard surfaces reflect sound well, creating echoes, while softer surfaces like carpets absorb sound, reducing echo. 

How Do We Measure Sound? 

Sound is measured in decibels, also known as its sound energy density level or sound pressure. 

What Is the Speed of Sound? 

Sound Energy | Speed of Sound Illustrationsource

Several factors can affect the speed of sound, like air temperature, the material the sound wave is passing through, and the sound wave frequency, for example.  

On Earth, at sea level, given an air temperature of 59 degrees Fahrenheit (15 degrees Celsius), the speed of sound is 761.2 mph (1,225 km/h). Sound moves faster through warmer air. As such, the higher in the atmosphere you are, the lower the required speed is to break the sound barrier. 

For example, the first aircraft to break the sound barrier and fly at supersonic speed was a Bell X-1 rocket-powered research plane. On October 14, 1947, the aircraft was towed high into the atmosphere and released. It broke the (local) sound barrier at 662 miles per hour (1,066 km/h). 

A sonic boom happens when aircraft go faster than the speed of sound. A sound like thunder is heard because the air gets pushed aside at great force, creating a shock wave. The displaced, pressurized air particles move outwards in all directions, and the pressure release from the shock wave is heard as a sonic boom. 

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What Is the Doppler Effect? 

Sound waves can play tricks on your ears in what is known as the Doppler Effect. 

For example, a car approaching you has a high sound pitch that lowers once it has driven past you, despite the car’s noise production not changing at all. If you were sitting in the vehicle, you wouldn’t notice any change in the car’s noise at all. The car’s sound wavelength frequencies stay the same throughout approaching and passing you. 

However, the car’s speed as it moves towards you makes the sound waves hit your ear at a faster rate or frequency than the vehicle is making them. That makes the engine’s pitch sound higher. The opposite occurs once the car passes you — the sound waves come to your ear more slowly and at a lower frequency, making it sound lower. 

Why Can’t You Hear Sound in Space? 

Space is a vacuum, with no air molecules for sound waves to vibrate. Sound is a mechanical wave, and so it cannot travel through a vacuum. There are no air molecules in the vacuum that the sound wave can vibrate. 

We can make it visual by thinking about a stadium full of people performing a stadium wave. The people are the air molecules, and they move — or vibrate — to keep the stadium wave going. Sound waves (the stadium wave) can move when there are air molecules (people). 

There are no air molecules (people) in a vacuum, so the sound wave cannot travel and make a noise, just as there is no stadium wave without people. 

Practical Uses for Sound Energy

Sound Energy | Waves Illustrationsource

Sound energy is not limited to enabling us to communicate and hear what is happening around us. Recording sound is one thing, but now we can use sound energy in many ways to improve our lifestyles. 

How Is Sound Energy Used? 

Sound energy is beneficial energy. Day-to-day, sound energy allows us to know when telephones are ringing, listen to music, communicate by talking, and hear a cargo truck honking its horn to warn of danger. These are just some examples of sound energy. 

Ultrasound — sound energy vibrations at a pitch too high for humans to hear — is critical to the medical field. Ultrasound uses the same echolocation method to show expectant moms their developing baby via a scan. 

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Ultrasound can also break up kidney stones or be used to scan organs. 

Meanwhile, sonar allows ships to navigate and search the seas, chart the seabed or look for sunken vessels.  

Does Sonar Use Sound Waves? 

Sonar stands for Sound Navigation and Ranging. Sonar has been used extensively at sea to chart the oceans, locate hazards, search, and more. 

Sonar uses sound waves because sound waves travel farther in water than radar or light.  

Active sonar pulses sound waves into objects and “listens” for echoes that can help map the investigated area. Passive sonar involves “listening” for sound waves in the ocean, such as other boats or whales. 

What’s the Difference Between Sound Waves and Radio Waves? 

We’ve seen that sounds are made of waves. When we listen to the radio, it produces sound. Still, sound waves and radio waves are fundamentally different from each other.  

A radio receives waves that are transmitted. The critical difference between sound waves and radio waves is that the radio wave is a type of electromagnetic wave. In contrast, sound waves are vibrations that make a mechanical wave. 

Radio waves can also travel through vacuums, unlike sound waves. That’s why satellites like Voyager 1 communicate with the Earth using radio waves. 

Can Sound Energy Be Converted to Electrical Energy? 

Sound Energy Group | Singing into Micsource

Yes, we can convert sound energy into electric energy. A widespread example is a microphone. 

When someone speaks or sings into a microphone, the sound energy travels down the mic to hit a diaphragm. In turn, the diaphragm vibrates, moving a magnet near a coil. The microphone now produces an electrical signal. 

The electrical signal from the microphone usually heads to a loudspeaker, and the loudspeaker then converts the electrical signal back into sound waves. As a result, you’ve got your concert, karaoke, or conference event. 

Research into turning noise into valuable electrical energy to power appliances is at a very early stage. As seen with the microphone, it is possible, but sound to electricity conversion at beneficial levels remains theoretical more than practical. 

You can, however, perform some pretty awesome acoustic levitation experiments with sound waves and sound energy. 

Who Discovered Sound Energy? 

Several famous names have helped in the cause of discovering sound energy. 

  • The Greek philosopher Pythagoras experimented with vibrating string properties as early as the 6th century BC.  
  • Aristotle hypothesized that sound waves propagate in air through the motion of the air. 
  • Roman architectural engineer Vitruvius successfully deduced sound wave transmission mechanisms in the 1st century BC. 
  • Galileo studied sounds waves and acoustics in the 16th and 17th centuries, elevating the study to a scientific level. 
  • French mathematician Marin Mersenne furthered the vibration study, providing three laws that form the basis of modern musical acoustics. 
  • Robert Hooke, an English physicist, was the first to produce a sound wave with a known frequency. 
  • In the late 17th and early 18th centuries, the studies of French physicist Joseph Sauveur examined the relationship of waves, pitch, and frequencies. Many acoustic terms come from his work. 

Do Animals and Humans Hear Different Sound Waves? 

Sound Waves | Dog Hears Sound's Energysource

Animals and humans have different hearing ranges, meaning that we hear different sound wave ranges from other creatures. 

Every species has a hearing range, and often some of those ranges are shared. These frequency ranges are measured in Hertz (Hz) and Kilohertz (kHz). 

Humans can detect sound waves from 20 Hz up to 20,000 Hz. 

As a general rule, smaller mammals detect higher ranges and larger animals lower ranges.  

An elephant has a range of 16 Hz to 12,000 Hz. Many noises they make are undetectable to the human ear. A cat’s range is from 45 Hz to 64,000 Hz — they will hear things at the higher range that humans and elephants will miss. 

Dogs often hear high-pitched noises we are entirely oblivious to because their range extends up to 45,000 Hz. 

Sound Energy Shapes Our World 

Sound energy is much more than hearing noises. We use our hearing to make sense of the sound energy that surrounds us. 

The old riddle about a tree falling in a forest with no one there to hear it — does it make a noise? Understanding sound energy means you know that the falling tree makes air particles vibrate, but it does not make a sound. It makes sound energy, and it only makes a noise if you are there to receive the vibrating sound waves for your brain to interpret as noise. 

For more fascinating facts about energy and natural phenomena, be sure to browse more of the Amigo Energy blog 

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