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11. Sound eLearn.Punjab

(b) Area of the vibrating body:

The loudness of sound also depends upon the area of For your information

the vibrating body. For example, sound produced by a Thin-walled glass goblets can vibrate when hit
large drum is louder than that by small one because by sound waves. This is due to a phenomenon
of its large vibrating area. If we strike a tuning fork on of sound known as resonance. Some singers
a rubber pad, a feeble sound will be heard. But if the can produce a loud note of particular frequency
vibrating tuning fork is placed vertically on the surface such that it vibrates the glass so much that it
shatters.

of a bench, we will hear a louder sound. From this we

can conclude that the loudness increases with the area of the vibrating body and vice versa.

(c) Distance from the vibrating body:
Loudness of sound also depends upon the distance of the vibrating body from the listener. It is
caused by the decrease in amplitude due to increase in distance.
Loudness also depends upon the physical condition of the ears of the listener. A sound appears
louder to a person with sensitive ears than to a person with defective ears. However, there is a
characteristic of sound which does not depend upon the sensitivity of the ear of the listener and it
is called intensity of sound.

Pitch: Pitch is the characteristic of sound Interesting information
by which we can distinguish between a
Some people use silent whistle to call dogs
shrill and a grave sound. whose frequency lies between 20,000 Hz to
25,000 Hz. It is silent for human but not for dogs
It depends upon the frequency. A higher pitch means a because the audible frequency range for dogs is
much higher.

higher frequency and

vice versa.

The frequency of the voice of ladies and children is higher than

that of men. Therefore, the voice of ladies and children is shrill

and of high pitch. The relationship between frequency and pitch

is illustrated in Fig. 11.8.

Fig 11.8: Variation of pitch with Quality: The characteristic of sound by which
frequency we can distinguish between two sounds of same

loudness and pitch is called quality.

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