We know that vibrations created by the body or object produce sound. There are different types of sound produced depending on the frequency. Sound is a mechanical wave that travels from one location to another. Sound travels through in the form of waves with the help of particles. The wave is said to undergo transmission/refraction, reflection or diffraction while moving. During transmission it also undergoes changes in the properties or behaviour of sound. An echo is created when a sound wave is reflected off a distant surface. Let us know more about echo and also the difference between echo and reverberation in this article.
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Propagation of Sound Waves
Propagation of sound is dependent on the medium through which it travels. The velocity of sound waves moving through the air can be reduced by high wind speeds that dissipate the energy of the sound wave. Sound waves feature particles of the medium through which it travels. Speed of the sound waves is affected by temperature. The viscosity of the medium determines the rate at which sound is attenuated.
When sound is transmitted, the sound in the audible range i.e., 20 Hz to 20 kHz can be heard by the human ear. Sound below or above the audible range, cannot be heard. Sound is differentiated based on the pitch, quality and loudness.
Echo and Reverberation
Sound and echo seem to be similar concepts, but they are not. They are different phenomena of sound. When the sound is repeated when the sound wave is reflected, it is known as echo. Echo is heard when space is large.
Example: imagine standing in an empty room and shouting “Hi”. You can hear “hi”…“hi”…”hi” repeated sounds in a fading pattern. This phenomenon is known as an echo. The sound of the voice goes out into the room, bouncing against walls until returning to our ears. The longer it takes for the sound to return, the more disturbing it will be.
We can also notice the echo that arises when crosstalk happens in phone calls.
When the reflection of the sound due to multiple sources happens within an enclosed system or when a sound wave is reflected off a nearby surface, reverberation happens. Reverberation is the reflection of sound waves created by the superposition of such echoes. Let us know the difference between echo and reverberation.
Difference Between Echo and Reverberation
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Echo |
Reverberation |
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It is the reflection of a sound wave off a surface. |
It is created by the reflection of sound waves created by the superposition of echoes. |
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It is clear and distinguishable. |
It is less clear comparatively. |
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When the distance between the source and the reflecting body exceeds 50 feet, an echo is heard. |
When the distance between the source and the reflecting body is relatively small, reverberation can be heard. |
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Echo is formed in both open and closed spaces. |
Reverberation occurs in closed spaces with multiple reflecting objects. |
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The echos can be used to calculate distance of the object. |
The distance of a reflecting object cannot be determined by the reverberation, since the travel time is too small. |
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The minimum distance of a reflecting object is 17.2 m. |
No specified minimum distance. |
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Related links |
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The below video helps to completely revise the chapter Sound Class 9
Frequently Asked Questions on Sound
What is the sound?
Sound is the vibration created by the body or object.
Which has more clarity, echo or reverberation?
Echo.
What is the audible range of sound?
20 Hz to 20 kHz.
What is the minimum distance between source and reflecting object to produce an echo?
The minimum distance of the reflecting object should be 17.2 m.
How is sound differentiated?
Sound is differentiated based on:
- Pitch
- Quality
- Loudness
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