Take time to read the previous verses to understand the context - adults were misusing God's house and children were singing praises for God's work. Jesus gives us meaning through God's inspiration of Psalm 8:6.
How do we lift our voices in praise? To God? Or people around us? Both, really. Praise is to Him and for Him, but let others hear to learn and join in.
Praise ye the Lord for His excellent greatness.