The Characteristics of Sound
These are sounds that have some characteristics that make them different. Following are the characteristics of sound.
The Characteristics of sound by which we can distinguish between loud and faint sounds is called loudness. Whenever two friends are talking to each other, their voices are low, but when addressing a public gathering our voice is loud.
FACTOR ON WHICH THE LOUDNESS DEPENDS
The loudness depends on the following factors.
(1) The maximum displacement of the body on either side of the equilibrium position called amplitude.
(2) The loudness and faintness of the sound depend upon the amplitude of the vibrations the greater than amplitude the louder the sound. If you sing softly, the sound amplitude is small and the sound is faint. But if you use more energy to sing, the amplitude is greater and the sound is louder. Similarly, the sound is faint when the drum is struck lightly. In this case, the membrane of the drum has a small amplitude through which it vibrates when the drum is struck strongly the membrane of the drum vibrates through a greater amplitude and hence we hear a loud sound.
(2) SURFACE AREA OF THE VIBRATING BODY
A School bell has a large area and therefore it produces a loud sound as compare sound of a cycle ball because it has a small area. The drum (dhol) produces a loud sound compared with that produced by a dholak (a small Drum) Thus the larger the area of the vibrating object the louder the sound produced.
(3) DISTANCE OF THE BODY PRODUCING THE SOUND
The loudness of sound also depends upon the distance of the sources of sound from the listener. We move away from a drum being Beaten violently to avoid the uncomfortable loud sound. Similarly, when the train is far away from the station we hear a faint sound but as soon the train comes near the station the sound produced train becomes louder.
The characteristics of sound by which we can distinguish between gave and shrill around is called pitch. High pitched sound Is shrill and low pitched sound is grave. We can distinguish the sound of a pigeon and a crow and the sound of a man woman and children due to pitch when a body vibrates it produces a certain number of vibrations (sound waves) in a second.
The number of vibrations per sound is called the frequency of the vibrating body has a greater frequency than a slower vibrating body. This can be demonstrated by an activity described below.
Rotate the wheel of a bicycle. Hold a piece of cardboard against the spokes of the wheel so that it produces sound. When you rotate the wheel slowly you hear a grave sound. On increasing the speed of the wheel, the frequency of the sound increases and the sound becomes more shrill.
The characteristic of sound by which we distinguish sounds produced by the different bodies is called quality. If your friends are talking in a room you can recognize them by listening to their voices. Similarly, if different musical instruments are played together the sound of these instruments can easily be distinguished due to the quality of sound.