Page 23 - Physics 10_Float

SOUND

For example, sound produced by a large drum is For your information
louder than that by small one because of its large Thin-walled glass goblets can
vibrating area. If we strike a tuning fork on a rubber vibrate when hit by sound
pad, a feeble sound will be heard. But if the vibrating waves. This is due to a
phenomenon of sound known
tuning fork is placed vertically on the surface of a
as resonance. Some singers
bench, we will hear a louder sound. From this, we can can produce a loud note of
conclude that the loudness increases with the area of particular frequency such that
the vibrating body and vice versa. it vibrates the glass so much
that it shatters.
(c) Distance from the vibrating body: Loudness of sound Interesting information
also depends upon the distance of the vibrating body Some people use silent whistle
from the listener. It is caused by the decrease in to call dogs whose frequency
lies between 20,000 Hz to
amplitude due to increase in distance.
Loudness also depends upon the physical condition of 25,000 Hz. It is silent for
human but not for dogs
the ears of the listener. A sound appears louder to a because the audible frequency
person with sensitive ears than to a person with range for dogs is much higher.
defective ears. However, there is a characteristic of
Low pitch
sound which does not depend upon the sensitivity of
Low
the ear of the listener and it is called intensity of sound. frequency

Pitch: Pitch is the characteristic of sound by which we can High
distinguish between a shrill and a grave sound. frequency
High pitch
Fig 11.8: Variation of pitch with
It depends upon the frequency. A higher pitch means a higher
frequency
frequency and vice versa. The frequency of the voice of ladies
and children is higher than that of men. Therefore, the voice of For your information
ladies and children is shrill and of high pitch. The relationship Tuning fork
between frequency and pitch is illustrated in Fig. 11.8. (a)

Flute
Quality: The characteristic of sound by which we can
(b)
distinguish between two sounds of same loudness and pitch
is called quality.
Clarinet
(c)
While standing outside a room, we can distinguish between
the notes of a piano and a flute being played inside the room. Fig 11.9: Sound waveforms
This is due to the difference in the quality of these notes. produced by (a) a tuning fork,
(b) a flute, and (c) a clarinet,
are all at approximately the
Figure 11.9 shows the waveform of the sound produced by a same frequency. Pressure is
tuning fork, flute and clarinet. The loudness and the pitch of plotted vertically, time

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