Echoes are discrete sound reflections from a distant surface which, if they are of sufficient intensity and time delay, can be heard distinctly from the direct sound, ie you hear the same sound twice in quick succession. The expression 'echoey' is often used to describe the sound heard in an enclosed space which is particularly reverberant or 'lively'. This is actually the wrong use of the term as, perhaps surprisingly, echoes are a rare phenomenon in most normal sized and occupied enclosed spaces. However excessive reverberation and noise can be controlled by the introduction of sound absorptive treatments, such as suspended acoustic ceilings.