One day, a Brahmin from a village named Harinadi (in Jessore district) started a debate with Srila Haridas Thakur on this (above mentioned) subject. He argued that the names of the Lord should be meditated upon and that there was no reason to chant them aloud. He wanted to know in which scripture it was stated that one should chant aloud.
In answer to these questions, Srila Haridas Thakur gave a detailed account of the glories of the Holy Name. He said that loud chanting of the Holy Names was a hundred times more powerful than japa. Through the loud chanting of the Names, even the birds, animals and other creatures are also saved. Animals, birds, insects and other creatures are unable to speak, but if they just hear the Holy Name, they can all cross over. If you chant the Holy Names silently, then you yourself will be saved, but if you chant aloud, then you will benefit others. Therefore, all the scriptures state that by the loud chanting of the Name, a hundred times greater result can be obtained.
(Chaitanya Bhagavat 1.16.280-2)
japato harinamani sthane shata-gunadhikah
atmanam ca punaty uccair japan shrotnn punati ca
Someone who chants the Holy Names aloud is a hundred times better than one who performs japa, because the one who is chanting ‘japa’ simply benefits himself, while the person who chants ‘japa’ aloud not only does good for himself, but for all those who hear him as well. Who is better, the person who earns money and spends it all on himself, or the one who uses his money to support a thousand others? Through japa, one takes care of his own spiritual life, while through uccha-sankirtan, all living beings are benefited. This is the reason for its being considered superior.