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SOUND - Coggle Diagram
SOUND
PROPAGATION OF SOUND-
- it propagates through the medium. The vibrations disturbs the molecules around it and causing the other molecules to vibrate. Since the molecules are tightly packed in a solid, sound travels fastest through it.
It travels in the form of Compression and rarefaction. When the vibration moves outward it creates a high pressure zone called compression and when it moves inward it creates a low pressure zone rarefaction. This changing of high pressure and low pressure zones sends out sound in the form of waves. The distance between the two consecutive compression and rarefaction is called wave length and is represented by λ.
SPEED OF SOUND:-
- Speed of sound increases with the density of medium as the vibrations can be transmitted faster.
- When the temperature is hot, the molecule tend to vibrate faster, so speed of sound is faster in Hotter temperatures.
- It is measured in m/s.
- loudest sound is produced by the blue whale and it can be heard 800 kilometers away.
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Reflection of sound and echo-
- Repetition of sound is called echo. When sound waves hit an obstacle they are reflected back, this is called reflection of sound.
- The minimum distance for echo to be heard is 17 metres
- The successive reflections from the source of sound is called reverberations.
Absorption of sound-
- Curtains, gunny bags and asbestos absorb sound.
- Many reverberations are unpleasant and so large halls are packed with thick curtains to stop overlapping reverberations.
Uses of Echo:-
- SONAR- SOund NAvigation and Ranging
helps us measure distance of seas and proximity to objects by sending ultrasonic waves from a sound source that reflect of the nearest object and is sent back to the receiver. Using the time taken you can measure the distance to the nearest object.
- In concert halls, echos are used to delay the abrupt ending of a song and make it sustain for a longer time period.
- Bats use echolocation to navigate through its surroundings. It emits ultrasonic waves that reflect of an obstacle and is received by the bat. This helps them navigate through its surroundings.
MUSIC AND NOISE-
- Music refers to the sound that produces pleasing sensation in our ears. This happens when the vibration patterns are regular.
- Sound that produces an irritating sensation in the ears is called noise.
- sound level above 80 Decibels is harmful and 60-65 is normal range
NOISE POLLUTION
- noise is derived from Latin. It means Nausea or sickness. Continuous noise that disturbs the environment is called Noise pollution.
- It can cause partial or total loss in hearing, stress, high BP, Change in sleep pattern, irritation, headache, unconsciousness, and possibility of heart attack on sudden exposure.
REDUCING NOISE POLLUTION
- Industrial zones should be far away from cities and its machines should be checked regularly.
- Automobiles should have silencers(no pls no)
- creating silence zones in and around the hospitals
- restricting guidelines on loudspeaker use in public
PRODUCTION OF SOUND-
- Main source of sound is vibration.
- When a body is in a to and fro motion about a mean position, it is called an oscillatory or vibratory motion.
- Vibration is the rapid to and fro motion about a mean position
- When an object vibrates, The air column around is also vibrates and sends the vibration through the air. this is how sound travels.
- Sound needs a medium for propagation.
INTRO-
- Sound is the form of energy that enables us to hear things.
SOUND OF MUSICAL INSTRUMENTS:-
- String instruments - Sound is produced by the vibrating string. Length is altered for varying pitch. Thick wires produce a low pitch and thin wires produce a high pitch noise. Guitar, Ektara, Santur.
- Wind Instruments- Sound is produced by vibrating air column. Air is blown into hollow pipes and it vibrates. Pitch can be altered by changing length of the air column.
- Percussion Instruments- Sound is produced by the vibrating of the stretched membrane on the body are usually made of wood and metal or clay.
THE HUMAN VOICE BOX:-
- sound is produced by the larynx or voice box.
- When we talk, air is from our lungs is blown through the trachea and is passed through a small slit between our vocal chords.
- The air makes the stretched thin vocal chords vibrate.
- Voice is changed by changing the thickness of vocal chords.
AUDIBLE AND INAUDIBLE SOUNDS:-
- 20 - 20k Hz (Sonic and Audible sound)- All sound in this range can be heard by humans.
- below 20Hz- Infrasonic sound elephants, rhinoceros use it to communicate and it is used for Earthquake detection.
- Above 20k Hz- Ultrasonic sound used by bats to navigate and search for food in dark, heard by dogs and dolphins.