What is echo?

By- Master Rohan Chakraborty

Dictionary meaning of echo?

• ech·o/ˈekō/• 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".

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.

• 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.

• 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?

•

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.