Characteristics of Sound (An In-depth Look)

The sensation felt by our ears is called sound. It is a form of energy which makes us hear. We hear several sounds around us in our everyday life.

We know that sound travels in the form of wave.

A wave is a vibratory disturbance in a medium which carries energy from one point to another without there being a direct contact between the two points.

We can say that a wave is produced by the vibrations of the particles of the medium through which it passes.

There are two types of waves: Longitudinal waves and Transverse waves. Longitudinal Waves: A wave in which the particles of the medium vibrate back and forth in the ‘same direction’ in which the wave is moving.  Medium can be solid, liquid or gases. Therefore, sound waves are longitudinal waves. Transverse Waves: A wave in which the particles of the medium vibrate up and down ‘at right angles’ to the direction in which the wave is moving. These waves are produced only in a solids and liquids but not in gases.

1. Wavelength

The minimum distance in which a sound wave repeats itself is called its wavelength. That is it is the length of one complete wave. It is denoted by a Greek letter λ (lambda).  We know that in a sound wave, the combined length of a compression and an adjacent rarefaction is called its wavelength.

2. Amplitude

When a wave passes through a medium, the particles of the medium get displaced temporarily from their original undisturbed positions. The maximum displacement of the particles of the medium from their original undisturbed positions, when a wave passes through the medium is called amplitude of the wave. In fact the amplitude is used to describe the size of the wave. The S.I unit of measurement of amplitude is metre (m) though sometimes it is also measured in centimetres.

Did you know that the amplitude of a wave is the same as the amplitude of the vibrating body producing the wave?

3. Time-Period

The time required to produce one complete wave or cycle or cycle is called time-period of the wave. Now, one complete wave is produced by one full vibration of the vibrating body. So, we can say that the time taken to complete one vibration is known as time-period.

4. Frequency

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The number of complete waves or cycles produced in one second is called frequency of the wave. Since one complete wave is produced by one full vibration of the vibrating body, so we can say that the number of vibrations per second is called frequency. The frequency of a wave is the same as the frequency of the vibrating body which produces the wave.

5. Velocity of Wave (Speed of Wave)

The distance traveled by a wave in one second is called velocity of the wave or speed of the wave.

What is the relationship between Velocity, Frequency and Wavelength of a Wave?

Velocity = Distance travelled/ Time taken

Let v = λ / T
Where T = time taken by one wave.
v = f X λ
This formula is known as wave equation.
Where v = velocity of the wave
f = frequency
λ = wavelength
Velocity of a wave = Frequency X Wavelength

This applies to all the waves like transverse waves like water waves, longitudinal waves like sound waves and  the electromagnetic waves like light waves and radio waves
Therefore we have learnt various characteristics of sound waves.