Perhaps then it is quite significant that this statement from Hebrews tells us that Jesus prayed out loud. Obviously we know He did this when He was teaching the disciples to pray the Lord's Prayer, and when He was blessing meals that they shared, but the Bible also makes it clear that Jesus prayed out loud while He was by himself. (See Matthew 26 and John 17). Why would Jesus do that? Jesus criticized the prayers of hypocrites who prayed aloud for the sake of being overheard, so Jesus' motivations must have been different. Perhaps He was modeling for us a way to stay focused. When you pray out loud, your mind doesn't wander off nearly as much because words aren't nebulous. I do not pray out loud all of the time, by any means, but I do find it fruitful to speak out loud some of the time.
On occasion, I also enjoy praying the Psalms, and many, if not most, of them have lines about praying aloud. They have phrases like "To you I call," "I cry out," "I call to the LORD," "when I call to you," and "To the LORD I cry aloud." There is scholarly support that although we've changed these expressions "into metaphors of the soul" the Israelites were literally speaking them out loud. (Paul E. Miller, A Praying Life) It might not feel totally instinctual at first, but for me, praying aloud grows more and more natural the more I do it. As an aside, I also think it helps to have prayed aloud in groups. Corporate prayer has been a source of incredible blessing in my life, and it has probably helped me feel more comfortable hearing my own irritating voice talking to God.
This week may we ponder why it is that praying aloud by yourself feels awkward. Where did those feelings come from? Then may we boldly speak out loud to God. After all, Jesus did and that's reason enough, don't you think?