Joshua 6: And the armed men went before the priests that blew with the trumpets, the priests going on, and blowing with their trumpets. And Joshua had commanded the people, saying, You shall not shout, nor make any noise with your voice, neither shall any word proceed out of your mouth, until the day I bid you shout; then shall you shout.
Soon after - - there was persecution and as Peter relayed to the believers what was happening; this time their voices were loud as they prayed. Acts 4:24 They LIFTED up their VOICE to God with one accord, and said, Lord, behold their threatening: and grant unto your servants, that with all boldness they may speak thy word, By stretching forth your hand to heal; and that signs and wonders may be done by the name of thy holy son Jesus. And when they had prayed, the place was shaken where they were assembled together; and they were all filled with the Holy Ghost, and they spoke the word of God with boldness.