Every spiritual activity is generally based upon some scientific theory. In earlier times, our temples used to have big brass bells in front of the deities. When a visitor used to ring the bell, its loud sound would render him thoughtless, causing the deity's image get captured in his still mind. On this basis, sankirtan has become an effective medium for concentrating our mind through the sound waves. Hari naam Sankirtan is actually a divine harmony of music (Naad Brahm) and words (Shabad Brahm) which lets the listeners forget about their physical existence and get absorbed in Him.