Question

State two necessary conditions for hearing a distance echo.

Answer 1

1. Sound reflection occurs when sound travels from one medium to another, hits the medium's surface, and bounces back into the same medium.
2. An echo is a delayed reflection of sound that reaches the listener after the main sound has passed.
3. The distance of the reflecting surface from the source and the listener determines how long it takes to arrive. Hearing an echo requires the following conditions:

3.1 The distance between the sound source and the location where it is reflected must be at least 17 meter.

3.2 The time between hearing the original sound and hearing the echo must not be shorter than 0.1 second.