Question

Why is echo weaker than original sound?

Answer 1

because the original sound collides with the obstacles and it becomes weak (echo)
:)
hope it helps

Answer 2

the echo is weaker than original sound because eacho is the reflect sound wave that will hear on 0.1 sec. at any distance but, original sound is not reflect sound it will non-uniform in perpendicular or transfer wave at high decibel (dBs) .so,the echo is weaker than an original sound.