Q.What do you mean by an echo?

[!TLDR] An echo is the original sound heard again, a short while later, because it reflected off a distant rigid surface back to the listener. [!ANSWER] The repeti …

An echo is the repetition of an original sound, perceived by a listener as a genuinely SEPARATE, distinct sound, caused by that sound reflecting off some rigid surface located at a distance from the source (sound obeys the same laws of reflection as light). For the reflection to be heard as a distinct echo rather than blending into the original sound, it must return at least 0.1 second after leaving (since the human brain retains a sound sensation for about that long), which in turn requires the reflecting surface to be at least about 17.2 m away (at 22°C). Shouting in a hilly region, or into a large em …

State the definition directly and mention the underlying reflection- …

Confusing echo with reverberation -- an echo is a single, clearly SEPARATE repetition (surface far enough away), while reverberation is the MERGED, p …