Question

Sir I am Shaun job of class 9. I haven't a doubt regarding physics on
the topic sound.This is the question
Is an echo "the repetition of sound by the reflection of sound" or is reverberation " the repetition of sound by the reflection of sound"
Thank you for your time Sir
Yours sincerely
Shaun

Answer 1

the repetition of sound by the reflection of sound.
The repetition of sound caused by reflection of sound waves from an obstacle is known as an echo.
For hearing distinct echoes, the minimum distance of the obstacle from the source of sound must be 17.2 m.

When reflected sound travels a greater distance, such as a cliff, and takes more than one-tenth second to return, it is referred to as an echo.
Echo does not add to the original sound as reverberation does, but is perceived as a distinct repetition of the sound, usually slightly fainter than the original.

The repeated reflection that results in this persistence of sound is called reverberation.
While multiple reflection doesn't need to be distinctively heard by us as the reflector can be at a distance of less than 34 meters also. In this case, we won't hear the sound clearly.
If the distance travelled by reflected sound is short, such as in a auditorium, the sound will be reflected back to the source in less than one-tenth of a second. This effect is reverberation. Because there is such a small delay in the sound repetition, sometimes only a few milliseconds, reverberation is often perceived by a listener as adding fullness to the original sound.