In plain words
A doctor gave a child in the womb an ounce of apple juice every day by injection. After that boy was born, he came to love apple. That is, whatever feelings, whatever tastes, whatever things he experiences while in the womb, the very same he experiences, plainly, after he is born. So, when you want to purify all the impure air outside, if you sing the Name of God, all of it joins that electric energy. All of it turns into waves. These waves remain for ever. Until they reach a certain level they go on changing. Once past a level, they stay for ever.
A small example of this. Today, in Delhi, there is a programme on the radio at 7 o'clock. If at that same time we switch on a radio in Prasanthi Nilayam, the same words, the same voice come here. Have they laid a wire from Delhi to Prasanthi Nilayam? They join the electric waves, join the air, and little by little spread everywhere. So there is such great power in sound. Ghaṇṭasāla used to sing so sweetly. But today, though Ghaṇṭasāla has died, the tape recorder makes his voice heard. That is, all our sound joins the electric waves and is absorbed into them. Today the air has become badly polluted by evil sounds. By this holy singing of the Name of God that impurity can be purified to some extent. In the same way, thinking of God, japa of God, the Name of God, singing of God: all these have the power and strength to make the five elements holy. There is nothing else that purifies more than this.
The tongue was given for remembering the Name alone!
They have tried to spend some thousands of crores to purify the Gaṅgā.