"Everything is Energy and that's all there is to it" - Albert Einstein -
What is Energy?
Energy is one of the most basic concepts in physics, but also one of the hardest to define. There is no physical “essence” of energy, and no such thing as “pure energy”. It is always carried by something, usually in the form of movement.
In simple terms, energy can be described as the capacity for doing work, whereas “work” is the action of moving something against a force. Energy may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms. In fact, seven forms of energy are generally described, namely:
Electrical Energy
Chemical Energy
Thermal Energy
Mechanical Energy
Nuclear Energy
Sound Energy
Light Energy
In physics, energy (from Ancient Greek ἐνέργεια (enérgeia) ‘activity’) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light.
Energy can be converted in form, but not created or destroyed. The unit of measurement for energy in the International System of Units (SI) is the joule (J).
As the Russian physicist Lev Okun said, “The more basic a physical notion is, the more difficult to define it in words”. Thus, for energy, the best we can do is say it’s the capacity to cause movement.
What is Sound?
In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid, or solid.
In human physiology and psychology, sound is the reception of such waves and their perception by the brain.
Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in).
Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges.
What is Acoustics?
In physics, the study of sound is known as acoustics and includes all constructs of sound.
Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration, sound, ultrasound, and infrasound.
A scientist who works in the field of acoustics is an acoustician, while someone working in the field of acoustical engineering may be called an acoustical engineer.
An audio engineer, on the other hand, is concerned with the recording, manipulation, mixing, and reproduction of sound.
What is Sound Energy?
In physics, sound energy is a form of energy that can be heard by living things.
Only those waves that have a frequency of 20 Hz to 20 kHz are audible to humans. However, this range is an average and will slightly change from individual to individual. Sound waves that have frequencies below 20 Hz are called infrasonic and those above 20 kHz are called ultrasonic. Sound is a mechanical wave and as such consists physically in oscillatory elastic compression and in oscillatory displacement of a fluid. Therefore, the medium acts as storage for both potential and kinetic energy.
Around the world, it’s hard to find somewhere where noise is not part of the landscape. From the roar of traffic to the sound of musical instruments, humans make a lot of noise. There are many different types of sound ranging from the audible to the inaudible.
Sound sources may be pleasant or unpleasant to the human ear, depending on loudness, different pitches, types of sound, sound source, and sound intensity. Regardless, sound energy travels, and depending on the sound source and the intensity, sound can sometimes be considered a pollutant.
So what is sound energy, exactly?
In simple terms, sound energy comes from vibrations moving through something. Solids, liquids, and gases all transmit sound as energy waves.
Sound energy is the result when a force, either sound or pressure, makes an object or substance vibrate. That energy moves through the substance in waves. Those sound waves are called kinetic mechanical energy.
Sound energy is turning sound into electricity. Microphones and speakers are examples of sound becoming electrical energy.
When we hear a sound, we are experiencing sound waves funneling into the ear canal and moving the eardrum, much like a drum head vibrates when struck. Different sounds make different vibrations that affect how the eardrum moves.
The vibrations travel from the eardrum via ossicles to the cochlea (a fluid-filled organ), causing surface waves that strike hair cells. Depending on the location of the hair cells in the cochlea, the brain “hears” high- or low-pitched sounds via the auditory nerve. It then translates the initial vibrations of the air molecules in the sound wave into sounds we understand.
Why are Sound Waves called Mechanical Waves?
Sound waves are sometimes called mechanical waves because sound waves require a physical medium to propagate. Liquids, gases, or solid materials transfer the pressure variations, creating mechanical energy in waves.
Like all waves, sound waves have peaks and valleys. The peaks are called compressions, while rarefaction is the term used for the lows.
The oscillations between compression and rarefaction move through gaseous, liquid, or solid media to produce energy. The number of compression/rarefaction cycles in a given period determines the frequency of a sound wave.
How Are Sound Waves Measured?
Wavelength, period, amplitude, and frequency are the four primary parts of a sound wave, regardless of the wave type and the medium through which the sound travels.
Wavelength:
Imagine a wave traveling along a horizontal axis; in that case, the wavelength is measured as the horizontal distance between two successive and equivalent points on the wave. Thus, in basic terms, a single wavelength is one cycle between the two equal points.
Period:
A wavelength period is the time it takes a single wavelength to pass a certain point. Generally, a more extended period indicates a lower pitch.
Amplitude:
We measure sound amplitude (strength or level of sound pressure) by the height of the sound wave. It’s related to the relative volume of the sound. When the wave’s amplitude is significant — as from a loud sound — the wave is high. The reverse is also true; softer sounds produce waves with a smaller amplitude. Lower volume equates to lower decibel (dB) levels; a decibel measures sound intensity. Zero decibels equates to the quietest sounds a human ear can hear. Decibels increase by a factor of six. A normal speaking voice is 60 dB.
Frequency:
Hertz (Hz) measures a sound wave’s frequency. Hertz measures a sound wave’s cycles per second that pass a set point on the horizontal axis. (Remember, each process has one compression and one rarefaction.) The frequency sound waves are measured in hertz. Therefore, Hertz (Hz) indicates the number of cycles per second that pass a given location. For example, if, while speaking, your diaphragm vibrates at 900 Hz, your diaphragm generates 900 compressions (increased pressure) and 900 rarefactions (decreased pressure).
Pitch is a function of how the brain interprets sound frequency. A higher pitch is the result of higher frequency; lower frequency translates as lower pitch.
Is Sound Energy Potential or Kinetic Energy?
Sound energy can be both: either kinetic energy or potential energy.
An example might be that of a musical instrument. When the instrument is played, it generates sound waves, producing kinetic energy. But when that same musical instrument is at rest, only the potential for energy is there.
What is Vibrations & Oscillations?
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point.
Oscillation in physics occurs when a system or object goes back and forth along a fixed path repeatedly between two states or positions. A wave is a correlated collection of oscillations.
Familiar examples of oscillation include a swinging pendulum, alternating current, tuning fork, cords of musical instruments, etc.
Pendulum
Harmonic Oscillator
In simple words, vibration means quickly moving back and forth (or up and down) about a point of equilibrium. The vibration may be periodic (having a pattern) or random. Something that is vibrating may shake at the same time. If it vibrates in a regular way, it may produce a musical note because it can make the air vibrate.
Sound vibration (drum)
Sound vibration (strings)
Is Sound just Vibrations?
When we consider what defines sound in a physics context, it can be tempting to assume sound is just vibrations. While partially true, sound is much more complex than simple vibrations. When a sound source vibrates, it produces sound energy that travels through particle disturbances in the medium, effectively transmitting the sound. As a sound wave moves through a medium, it creates high and low pressure differences called rarefactions and compressions. These differences are the result of particles within the medium shifting from their original states and causing other particles to compress or expand as a result.
While a vibrating source creates sound energy, pressure differences make up the sound wave. Specific patterns of rarefactions and compressions are what give sounds their distinct characteristics, and ultimately, allow us to differentiate between noises, melodies, and other sounds.
How does Sound Energy produce Electricity?
Sound vibrations can become electrical energy through the principle of electromagnetic induction. Electromagnetic induction generates electrical current using a magnetic field.
When a magnetic field and a conductor, such as a wire coil, move in relationship to one another, electromagnetic induction occurs. As long as the conductor is in a closed circuit, current flows wherever the conductor crosses the lines of the magnetic force.
As we know, sounds constantly fill our acoustic environment. Like all energy, sound energy has the potential to generate electricity. Just like the sun provides unlimited solar energy and the breeze provides wind energy, sound energy is renewable because sentient beings and insentient objects alike constantly produce sound.
While sound waves and energy production principles have long been understood, the technology to convert sound energy to electricity is in its infancy.
"Everything is energy and that's all there is to it. Match the frequency of the reality you want and you cannot help but get that reality. It can be no other way. This is not philosophy. This is physics." - Albert Einstein -
"What we have called matter is energy, whose vibration has been so lowered as to be perceptible to the senses. There is no matter ... There is only Sound and Light. We are all Light Beings." - Albert Einstein -