How does an ECHO happen?
An echo is an eerie phenomenon that can occur under certain circumstances, and is caused by several conditions which must be just right. Let’s look at what causes an echo! Echos 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 metres per second, or 150 metres per half-second, it needs to trav
