basics of sound

1. Topic:
sound

2. Contents:
Production of sound.
Importance of sound.
Propagation of sound.
Characteristics of sound.
Speed of sound.
Echo & reverberation.
Range of hearing.
Noise & music.
Ultrasounds and its applications.

3. Production of sound:
 Sound is produce by vibration.
 By plucking, striking ,rubbing and blowing we produce sound.

4. Importance of sound:
Sound makes it possible for us to communicate with others.
Music.
Radio and TV sounds give us information and entertainment.
Horn sounds of vehicles keep us alert on roads.

5. Propagation of sound:
Sound requires a medium to travel from one place to other.
Medium may be gas, liquid or solid.

6. Characteristics of sound:
Sound produces longitudinal waves(particles move along the direction of
waves).

7. Echo:
 The sound waves produce by reflection of sound waves.
Distance must be 17
metes for echo.
Reverberation:
 Repeated reflections of sound is called reverberation.
We use sound absorber materials to get rid of
reverberation.
Such as fiber boards or rough plaster etc.

8.  Humans can hear sound between 20Hz to 2000Hz.
 The sound waves with frequency more than 2000hz are called ultrasonic.
 The sound waves with the frequency less than 20hz are called Infrasonic.
Audible range of sound(in Hertz) for few
animals.
Elephant 16-12000
Cow 16-40000
Cat 100-32000
Dog 40-46000
Bat 1000-1,00,000
Seal 900-2,00,000

9. Noise:
the unpleasant sound is called as noise .
Music:
The sound which pleasing to the ears.

10. Ultrasounds:
Ultrasounds are high frequency waves.
Frequency greater than 20,000Hz.
Applications:
 SONAR(sound navigation and ranging)
 Ultra sonography

11. Doppler effect:
Change in the frequency of sound waves due to relative motion of source and
observer.
Application:
 RADAR(radio detecting and ranging)