1. Sound
waves are longitudinal waves.
2. Sound
requires medium tor travel.
3. Sound
cannot travel through vacuum.
4. Study of
sound is known as acoustics.
5. Echo and
reverberation are due to the reflection of sound. For the production of echo
there should be a minimum distance of 17m between us and the reflecting
surface.
6. Bats can
fly in the dark because they can generate ultrasonic sound and if there is any
hindrance in their way the sound wave get reflected and they can change their
direction.
7. The
audible frequency of human ear is between 20 hertz and 20000 hertz.
8. Velocity
of sound in the air is 340 m/s.
9. Sounds
are distinguished from each other by pitch (frequency), loudness(intensity)and
quality.
10. Phonogram
is a machine to reproduce sound.
11. The speed
of sound depends on the medium the waves pass through.
12. SONAR
stands for sound Navigation and ranging. It uses ultrasonic waves.
13. Velocity
of sound in moist air is greater than in dry air.
14. Sound
travels faster in steel.
15. The
intensity of sound is measure in decibel.
16. During
night the allowed intensity of sound in hospital area is 40db.
17. Ultrasonic
sounds can be received and emitted by bats. While infrasonic sound can be
received by snakes.
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