What is echo

1. What is echo? By- Master Rohan Chakraborty

2. Dictionary meaning of echo? ech·o /ˈ ekō / Noun: A sound or series of sounds caused by the reflection of sound waves from a surface back to the listener: "the walls threw back echoes".

3. What’s exactly an ECHO? An echo Is a reflection of sound. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single reflection of the sound source. The time delay is the extra distance divided by the  speed of sound . 

4. Echoes happen because sound bounces off things. You probably knew that already. But something else has to happen as well; just bouncing won't make an echo. After all, you don't hear an echo when you yell in your bedroom, even though the sound is bouncing off the walls. 

5. The first requirement for an echo is  distance . Sound travels fast ... about 300 metres in one second. A really good echo will return to you after several long seconds ... that's what makes it  eerie . For our purposes, let's suppose that any sound that returns within half a second  will overlap with your own voice and  not  make a distinguishable echo . So how far must an echo travel in order to return at least half a second later?  

6. Remember that it must  go out  and then  come back  to you. At 300 meters per second, or 150 meters per half-second, it needs to travel at least 150 meters in total ... or 75 meters out and 75 meters back. As a result, to get a good echo, the sound  must bounce off something at least 75 meters away . Otherwise, it will return in  less  than half a second, and won't make a good echo.