Question

do we hear echo if the time interval between the original sound and echo is more than 0.1 second? if then why?

Answer 1

yes, we can hear an echo qhich is more than 0.1 seconds because the frequency on the sound wave is 0.1 sec. If it would be

Answer 2

When original sound is creat , this sound is strick to a wall or body it come back ,this sound is called eco sound.
The formula of eco sound is distance traveled and back distance by time taken
2d/t.