Question

what are the four conditions to hear an echo

Answer 1

(i) The time interval between source sound and reflected sound must be atleast 0.1s.
(ii) The minimum distance between the obstacle and source of sound should be atleast 17.2 m.

Answer 2

The four conditions to hear an echo are these:-

Explanation:

1. If we want to hear any echo properly, then the time difference between our original voice and the echo which we have, should be at least 0.1 seconds.
2. It is very important to have a reflecting surface which produces an echo sound.
3. There should not be any sound absorbing substance that will not produce the echo that is the sound
4. If we want to hear any echo properly, we must be at least 17. 2 meters away from that reflective surface, otherwise we will not be able to hear the echo properly.