Question

What is sound echo and how is it created ? Why does it happens only in few places and not everywhere ?

Answer 1

Dear student,

In audio signal processing and acoustics, Echo is a reflection of sound that arrives at the listener with a delay after the direct sound. The delay is proportional to the distance of the reflecting surface from the source and the listener. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single reflection of the sound source

So An echo is a sound which is caused by a noise being reflected off a surface such as a wall.
{or The repetition of sound caused by the reflection of sound waves is called an echo.}

Like all waves, sound waves can be reflected. Sound waves suffer reflection from the large obstacles. As a result of reflection of sound wave from a large obstacle, the sound is heard which is named as an echo. Ordinarily echo is not heard as the reflected sound gets merged with the original sound. Certain conditions have to be satisfied to hear an echo distinctly.

Why it happens in few situations

Example

In a well furnished house sound is reflected from the furniture of your room and comes to your ear quickly and you cannot perceive two of them

while in an empty room the sound takes longer path and hence longer time to reach your ear and hence you hear two different sounds and that's why echo is there.

Hope you understood
Regards