Characteristics of Sound Waves
The world is filled with sounds! We experience a cacophony of sound in our daily lives. Science helps us to decode sound-the amazing energy. A sound is a type of energy which travels as a wave away from its source. It is a mechanical wave which is produced by the back and forth vibratory movement of the particles of the medium through which it travels. The sensation reaches our ear, goes to our brain. ‘It’ gets processed by the brain, helping us hear the sound.
Longitudinal waves and transverse waves are two types of waves. A wave where the particles of the medium vibrate back and forth towards the same direction in which the wave is moving is called a longitudinal wave. The medium can be either solid, liquid or gas. Since sound waves move in the same pattern, they are described as longitudinal waves. These waves comprise ‘rarefactions’ and ‘compressions’ of a medium.
Rarefactions and Compressions
In longitudinal motion of air particles (particles of any medium), compressions are the regions where the air particles are compressed together. On the other hand, rarefactions are regions which are simultaneously created, where the air particles are spread apart. Hence, compressions and rarefactions are regions of high and low pressure respectively.
Transverse waves are described as waves in which particles of the medium move up and down along an axis which is at right angle to the direction of the wave. These types of waves are not only produced in gasses, but also in solids and liquids.
Characteristics of Sound Waves
Amplitude, wavelength, period, frequency and speed/velocity are the five characteristics of sound.
As a wave moves through a medium, it temporarily displaces the particles of the medium from their actual position. Amplitude of the wave is basically the maximum ‘displacement’ of the particles of the medium from their actual positions as it passes through them. In short, it ‘describes’ the size of the wave. ‘Meter’ is the S.I. unit of amplitude.
The ‘minimum distance’ in which a sound wave repeats itself is known as its wavelength. Basically, it is the length of one complete wave. The combined length of an adjacent rarefaction and compression is called the wavelength of a soundwave. The distance between the centers of two successive rarefactions and two successive compressions is ‘equal’ to the wavelength of the soundwave. ‘Meter’ is the S.I. unit of wavelength.
The time which is required for producing one complete wave/cycle is known as the period of the wave. One full vibration of the vibrating body can produce one complete wave. Hence. ‘Period’ is the time taken for completing one vibration. The unit of measurement of period is second (S) and is denoted by letter T.
Frequency of a wave is defined as the total number of cycles/waves which are produced in one second. It can also be described as the number of vibrations per second. For example, the frequency of the waves will be 10 Hertz and 10 cycles, if 20 vibrations are produced in one second. A sound wave will have a fixed frequency and will not change as it passes through different mediums. Hertz or Hz is the unit of frequency.
Velocity of the wave is the distance which is covered/traveled by a wave in one second. ‘Meters per Second’ is the unit of measurement of velocity. By dividing the distance traveled with the time taken, we can derive the velocity of a wave. We can also obtain velocity by multiplying the frequency of the wave with the wavelength.
This applies for all types of waves including transverse waves (like water waves), electromagnetic waves (light waves, radio waves etc), and longitudinal waves.
Greek philosopher Chrysippus, Roman architect Vetruvius, and Roman philosopher Boethius established that sound travels in the form of waves.
In this blog, we have discussed the characteristics of sound.
A wave where the particles of the medium vibrate back and forth towards the same direction in which the wave is moving is called a longitudinal wave.
Amplitude, wavelength, period, frequency and speed/velocity.