Echo is one of the acoustic defects that we often encounter in rooms. Echo occurs when a sound wave (acoustic) reflects off a potential obstacle and then returns to the listener. This sound is heard again after the original sound. We can only call this reflection of the sound wave an echo when the repeated sound reaches the listeners after 100 milliseconds or more. Before this time has elapsed, we can speak of reverberation.
In the case of an echo, the human ear is able to distinguish it as completely separate sounds. The phenomenon of echo can be found both in enclosed spaces and in open areas, for example, near mountain slopes or the edge of a forest.
The echo effect can also be used outside of room acoustics, among other things, in watercraft when constructing devices such as sonars. This way, obstacles in the water or sought-after objects can be located.
