Question

What is an echo? What factors are
to get a distance echo?

Answer 1

An echo is the phenomenon of repetition of sound of a source by reflection from an obstacle.To get echo, the obstacle must be situated at a suitable distance from the source.

Answer 2

echo is the reverberation or re sound of the actual sound
for hearing distant Echoes the minimum distance of the obstacle from the source of sound must be half of this distance that is 17.2 m this distance will change with the temperature of the air .Echoes maybe heard more than months due to the successive or reflections.