Characteristics of sound

Characteristics of sound

Sound has three characters.

1) Loudness
2) Pitch
3) Quality or timbre

Loudness of a sound: Loudness is the quantity of energy possessed by the sound.
Loudness is measured in bels, with the decibel (dB) being the commonly used practical unit. 1 decibel means \(\frac{1}{10}\) of bel. Loudness depends on a few factors.

Factors on which Loudness depends:

i) Distance between the source and the listener. When the distance between the source of the sound and listener increases the loudness decreases and when the distance between the source of the sound and listener decreases the loudness increases. 

ii) Area of the sounding body. The loudness of sound increases with the surface area of the vibrating object. A larger sounding body produces a louder sound, while a smaller one generates a softer sound. For example, a large bell sounds louder than a small one, and the sound of a dhak is more intense than that of a tabla. Because the area of sounding body dhak is greater than tabla.

iii) Presence of the resonance body. The loudness of sound is increased in presence of a resonance body.

iv) The loudness of sound is also influenced by the density of the medium. A denser medium tends to transmit sound more effectively, resulting in greater loudness. Conversely, as the density of the medium decreases, the loudness of the sound also diminishes. The loudness of the sound that passes through an iron tube will be greater than that passes through the air. 

v) Amplitude of the sound wave. More the amplitude more will be the loudness and less the amplitude less will be the loudness.

vi) Flow of media current. If the sound travels through air or water in favor of air current or in favor of water current then the loudness of sound appears to be greater in the listener's ear. If the sound travels against a water current then the loudness of sound appears to be less in the listener's ear.

2) Pitch of a sound: The second characteristic is the pitch. Pitch refers to how high or low a sound seems, often described by its sharpness or shrillness. If the sound is shriller then its pitch is greater and if shriller is less then its pitch is less. It depends on frequency. More the frequency more will be the pitch and less the frequency less will be the pitch.

       That is why female sound is Shiller than mail sound. Because the vocal cord of a female is softer than a male vocal cord. So the frequency of sound made by the female vocal cord is much greater than that made by the male vocal cord. A higher frequency results in a higher pitch of the sound. So the sound will be shriller.

3) Quality or timbre of a sound: If different sounds emitting from different musical instruments like setar, guitar, harmonium, etc having the same loudness and same pitch then we can differentiate sounds with quality. Quality or timbre is the property of sound that allows us to distinguish between sounds produced by different sources, even when they have the same pitch and loudness.