If you sing alone in your shrine, the vibrations return to you as a reaction. But in community singing, what you have is not a reaction but a wave of vibrations. They enter into the atmosphere and purify the polluted air.
Sathya Sai BabaI behave like you, moving, singing, laughing, journeying, but watch out for the blow I inflict all of a sudden, to chastise and to warn.
Sathya Sai Baba