Be still and know that I am God,
I will be exalted among the nations,
I will be exalted in the earth! Psalm 46:10
This verse it seems is taken by many as a guideline for the volume of praise. But lets look at the context of the chapter. The verses preceding this verse talk about natural disasters and nations going of to war, and then God breaks forth telling us to be still. To me it's like God is say, "Hey, chill out, and stop worrying. I got this!" To me this is not a call for God's people to praise him in a soft voice. I've talked about reverence being of utmost importance when it comes to worship, but a thorough study of scripture shows that the standard volume for praise is loud.
Shout to God with cries of Joy Psalm 47:1b
Shout with joy to God, all the earth! Psalm 66:1
And I could go on and on. Now there are times that call for quiet meditation and even silence, but if Scripture is going to be our guide, then we should "shout for joy" for all that God has done for us.