God hears our prayers anytime, anywhere, and at any volume. He hears even when we think our prayers to Him rather than voice them. God hears our prayers when we cannot put them into words— for example, when our hearts are too burdened or confused even to speak.
One of the best ways to grow in praying out loud is to practice listening to yourself reading prayers from the Scripture. You can start with the Lord’s Prayer in Matthew 6:9-13. Hearing your own voice as you pray out loud is an important step.