We know that sound is produced from everything. These days, our activities in fact entire human living is based on sound. We begin our day with an alarm clock followed by many variants of sounds such as music, noise, vehicles, etc. Basically sound is the most essential part of our lives. Every living thing such as the roaring of a lion, crying baby, ultimately when we pour water into a glass we witness the production of sound. Now the question that arose is what is sound?
A sound is a form of energy. The study of sound starts with the properties of sound waves and the types of sound waves. Basically sound is a form of wave or vibration. Human ears can sense the sound waves ranging from 20Hz to 20KHz, known as audible sound range. There are many variants of sounds such as pleasant sound, unpleasant sound, music, noise, soft, loud, etc. In this article, we will study the difference between sound noise music, what is meant by sound, what is the meaning of sound, types of sounds in physics, what is noise, etc.
Types of Sound
Before starting with types of sound, let us understand what is sound in physics? Sound waves are longitudinal, mechanical waves. Sound is caused by the back and forth vibration of the particles of the medium through which the sound wave is propagating. The vibrations of the object allow particles in the surrounding medium in vibrational motion, causing the auditory receptors to detect them. This is known as the sound.
Though all the bodies that vibrate in the air can indeed produce sound, we can not hear all of them. Our ears are sensitive to a certain frequency range, depending upon this fact there are only two types of sounds i.e., audible and inaudible sound. The audible sound ranges from 20Hz to 20KHz. The sound waves that are below 20 Hz are known as infrasonic sounds and the sound waves above 20KHz are known as ultrasonic sound.
Audible sound is further classified as pleasant sound and unpleasant sounds. So the pleasant sounds are the group of sounds that makes us feel relaxed like good music such as playing the piano, singing songs etc. At the same time, there are a certain set of sounds that will be unbearable or cause irritation to the hearing body like loud noises such as barking dogs, drilling machines etc. We can say audible sound can be classified into music and noise.
Properties of sound
Sound in itself consists of seven major properties that either make it audible or inaudible, noise or music to the human ears. Different species of animals hear distinct sounds that can be inaudible to humans because of the varying properties of sound.
Let us take a look at the properties of sound:
Frequency: Sound consists of sound waves. These waves are like the waves of water, they go up and down and then up again making a whole cycle. Frequency, or pitch, is the time taken by the soundwaves to complete an entire cycle. It is measured in hertz where one hertz (Hz) is equal to one cycle per second.
Amplitude: The intensity of the soundwave is called its amplitude. The higher the sound waves, the more the intensity and the greater the amplitude. In common man’s language, we call it the volume of the sound. If someone is shouting, it means the sound has high amplitude while whispering can be considered as having low amplitude.
Timbre: Have you ever heard two different instruments that play the same note yet sound so different? It is because they have different tones or timbres. Some frequencies that are lower in pitch are called subtones, while the ones higher in pitch are called overtones. Both of them combined to form ‘harmonics’ and give the sound distinct timbre or tones.
Envelope: Envelope is simply how a sound wave or sound behaves over a particular period. It is also called ADSR, which is short for attack, decay, sustain and release. These are four sub-properties of the envelope. The attack is how fast a sound reaches its highest volume, decay is when it drops before it sustains a constant volume and finally releases into the atmosphere, almost vanishing.
Velocity: The velocity of the sound is the speed at which the soundwaves travel through different mediums. Since, soundwaves use the medium of air to travel, the velocity of the sound can depend on different factors including humidity, temperature and density.
Wavelengths: The difference between consecutive crests of the sound wave is called wavelength. Audible sounds have longer wavelengths than inaudible sounds.
Phase: Phase is described as the difference between amplitude crests and troughs of two sound waves. It is measured in time, degree or distance. Two sound waves that have the same and are perfectly aligned to each other are said to be ‘in phase’; that is their phase difference is zero. It is important to know about the phase of sound to prevent ‘hollow’ sounds.
What is Noise and Types of Noise?
Now, what is noise? So, noise is a type of sound, it is really important to distinguish between what is noise and what is sound. Noise is a type of sound and it can be defined as a type of sound that can be unpleasant, unwanted, annoying or too loud for human ears.
Human ears are highly sensitive and excellent at identifying what is noise. Generally, noise is an annoying tone of sound that causes mild to major discomfort or irritation. These sound vibrations pierce through the background noise that accompanies our lives.
When it comes to measuring the different types of noise, we want to replicate how the human ear identifies noise to get an accurate interpretation of its impact. Thus, generally, we use something called the A-weighted frequency, which is much more sensitive between the 500 Hz and 6 kHz range. There are four different types of sound, as listed below:
Let’s discuss the four types of noise one by one as follows:
As the name suggests it is a type of noise that is produced continuously.
The examples of continuous noise are all the machines that run continuously without any breaks such as while riding a car we hear the sound of functioning parts like the engine, in factories large machinery produces continuous noise.
Intermittent noises are noises that are not produced continuously. Intermittent noises are produced continuously but with intermediate breaks.
The best examples for the intermittent noises are drilling machines, which we might have seen during the destruction or construction of any building we use drilling machines that produce unbearable sound. Another example of intermittent noise is drilling machines used by a carpenter or the dentist.
It is a type of noise characterized by a noise level of more than 40dB within a half-second with a duration of one second.
Impulsive sounds incorporate almost all unwanted, instantaneous sharp sounds.
Examples of impulsive sounds are bomb explosions, the fringe of weapons, etc.
Low-frequency noise is produced from the objects around us in everyday life. It is one of the difficult types of noise to reduce, and it makes a silent room still register sound levels around 30-40 decibels.
In an office setting, this noise is produced from a heating or ventilation system. In our house, it will arise from the ticking on a grandfather clock. Generally, we don’t even identify these types of noise unless we direct our attention towards them.
So, these are the different types of noise and what is the meaning of noise physics.
Let us have a look at the difference between sound and noise as listed below:
Difference Between Sound and Noise:
These are the important differences between sound and noise. Similarly, we can note the difference between the sound and music, music and noise, etc. Learning the difference between these will help us understand the terms in a better way.
What is Music?
Music, by its definition, is referred to as vocal and instrumental sounds occurring one after another to create a beautiful symphony of harmony and expression of emotion. A music sheet is the written or printed signs representing these vocal or instrumental sounds.
The process of putting sounds and tones in a rhythm, mostly combining them to produce a unified composition is known as making music. Music-making is as much science as it is an art.
To create melodious music, you would need a musical instrument or instruments, these instruments create sounds with string, wind, and brass using special kinds of sound waves – known as ‘standing waves.
A wave that looks like it isn’t moving is called a standing wave. It only changes amplitude but doesn’t travel through any medium. The standing waves are the result of two other things waves do, reflection and interference.
When a sound wave travels through a path, reaches its end and then travels back, reflections occur. That’s what happens when you send a pulse down a rope – it reaches the end, and then comes right back.
When we send a continuous wave down the rope, that’s when interference comes into play. The sound wave after reaching the endpoint of the rope is reflected; however, there are more peaks on the path. As the peaks pass each other, they interfere with one another, changing their sizes.
Usually, it results in the formation of crests and troughs that are of varying sizes and various distances apart. But at particular frequencies, the reflected waves interfere in such a way that you end up with a wave that seems to stay perfectly still, with only its amplitude changing. That’s a standing wave, and it can be produced by both, the strings and the air in pipes.
That is what makes music: standing waves with different frequencies correspond to different musical notes.
Did You Know:
Noise pollution causes hearing loss that is hazardous to human beings. People who are subjected to loud sounds regularly suffer hearing loss. The technical term used for this is Noise-Induced Hearing Loss (NIHL). Dangerous Decibels (an agency) researched the subject and discovered that out of the four million people in the United States who suffer from hearing loss, about 25% of those cases have NIHL.
About 30 million people in the United States are subjected to hazardous sound levels at their workplace every day, according to a study from 2005.
In 2015, the Centers for Disease Control and Prevention (CDC), found that mining was the industry with the loudest work environment, followed by manufacturing and construction. About one in eight of the workers in these and similar industries had hearing loss caused by their work environment.