What Is Sound?
A sound is a vibration that propagates through a medium in the form of a mechanical wave. The medium in which it propagates can either be a solid, a liquid or a gas. Sound travels fastest in solids, relatively slower in liquids and slowest in gases.
In physics, the sound is defined as
A vibration that propagates as an audible wave of pressure, through a medium such as a gas, liquid or solid.
In psychology, the sound is defined as
The reception of sound pressure waves and their perception by the brain.
What is a Soundwave?
A sound wave is the pattern of disturbance caused by the energy travelling away from the source of the sound. Sound waves are longitudinal waves. This means that the propagation of vibration of particles is parallel to the energy wave propagation direction. When the atoms are set in vibration they move back and forth. This continuous back and forth motion results in a high-pressure and a low-pressure region in the medium. These high- pressure and low-pressure regions are termed compressions and rarefactions, respectively. These regions are transported to the surrounding medium resulting in the sound waves travelling from one medium to another.
What Is Sound?
A sound is a form of energy, just like electricity, heat or light. Sound is one of the important senses of the human body. Some sounds are pleasant, and some are annoying. We are subjected to various types of sound all time. Sound waves are the result of the vibration of objects. Let’s examine some sources of sounds like a bell. When you strike a bell, it makes a loud ringing noise. Now, instead of just listening to the bell, put your finger on the bell after you have struck it. Can you feel it vibrating? This is the key to sound. It is even more evident in guitars and drums. You can see the wires vibrating every time you pluck it. When the bell or the guitar stops vibrating, the sound also stops.
The to and fro motion of the body is termed vibration. You can see examples of vibrations everywhere. Vibrating objects produce sound. Some vibrations are visible; some aren’t. If you pull and then release a stretched rubber band, the band moves to and fro about the central axis and while doing, so it also produces a sound. The sound moves through a medium by alternately contracting and expanding parts of the medium it is travelling through.
In physics, the sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
Sound is the form of energy that is produced when things vibrate. It propagates as an acoustic wave through solid, liquid and gaseous states. The human-audible sound ranges from 20 Hz to 20 kHz. The sound that has a frequency above 20kHz is known as ultrasound.
What we hear is the effect produced due to the to-and-fro motion of the particles in any medium. The to-and-fro motion is termed as vibration. Sound moves through a medium by alternately contracting and expanding parts of the medium which it is travelling through. This expansion and compression create a minute pressure difference that we perceive as sound. Hence, it is a mechanical wave of pressure and displacement
Sounds are of many types, depending on the pitch, loudness, amplitude, and frequency of the sound wave; but not all of them please our sense of hearing. Both noise and music are forms of sound. Music is what pleases our sense of hearing. It depends on numerous factors and varies from person to person. On the other hand, noise is defined as unwanted disturbing sound that is too loud and disruptive to our sense of hearing. Sometimes, the boundaries that separate musical sound from noise is blurry. What is music to someone, can be noise to somebody else.
Sound Wave Characteristics
After understanding what is sound, let us study the characteristics of the sound wave. The distance between two consecutive peaks or troughs is termed as the wavelength of the wave or the period. The number of cycles per unit time is termed as the frequency of the sound. Frequency is measured in cycles per second or Hertz.
The faster an object vibrates, i.e. the higher the frequency, the higher the pitch of the sound. The difference between the voices of a man and a woman must be clearly evident to you. The voice of a man has a lower frequency which contributes to the deepness of the bass in the voice. Women, in contrast, have a voice with higher frequency resulting in a higher shrillness or pitch.
Closing Our Ears When We Hear Loud Noise
If you hear a very loud sound, what do you do? You cover your ears. How do you think that helps? When you cover your ears, you shut off the air inside your ears from the rest of the atmosphere. The sound waves travelling around you are now unable to get through to your ear or the intensity of the sound you hear is greatly reduced. Blocking your ears creates a discontinuity in the medium due to which the flow of sound energy is disturbed. Through this, we can make a very important observation; Sound waves rely on the medium for propagation. The propagation of the sound wave is not possible through the vacuum. The medium here can be gas, liquid or solid. The speed of sound when it is travelling through a medium depends on the type of medium. The speed of sound when travelling through air is 343 m/s or 1,235 km/h.
Human Hearing and Speech
Humans can hear sounds ranging from 20 Hz to 20 kHz. Sounds with frequencies above the range of human hearing are called ultrasound. Sounds with frequencies below the range of human hearing are called infrasound. The typical sound produced by human speech has frequencies in the order of 100 to 1,000 Hz.
How do we create Noise?
Our ideas about objects in the case of both visual and auditory are subjective, as it depends from person to person. A person who listens to bands like Linkin Park or Rage Against the Machine will love the loud music but it is not the same with the one who prefers classical music or soft music. To that person, rock music will feel like noise. In such cases, the definition of Noise is somewhat subjective. Noise is everywhere, even when we are talking to each other in a room. In a classroom, if students talk while the teacher is teaching, they are creating noise. But human voice is not always classified as noise. It is considered noise when it is unwanted or disturbing to those who hear it.
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