Author had explained basic details of sound energy with scientific proper history. Architectural acoustic is also discussed to produce optimum sound effect in auditorium / seminar hall. Factors affecting the acoustic of building are explained. Complete working theory or mechanism of the human ear is written with modern research associated in its working. Overall control of musical notes in different musical instruments is discussed. Fundamental understanding and physics behind the sound waves, sound energy and music is written in depth. Basic working principle of many musical instruments is also covered.