The term 'Sound RETURN' can be broken down into two words, 'ECHO' and 'RETURN'. ECHO is a 4 letter word which refers to the reflection of sound waves off of a surface. It is often used in audio engineering and sound production to create a reverberation effect. RETURN is a 6 letter word which refers to the act of sending something back to its original source. In this context, it could refer to the sound waves being sent back to their original source after being reflected off of a surface. Together, the term 'Sound RETURN' refers to the process of sound waves being reflected off of a surface and then sent back to their original source.