Several months ago I found myself in a room and quite alone. This was the first time that I had been in such a situation in three and a half years. I took advantage of the opportunity to pray aloud. It was awkward.
Having been brought up in the gospel I was taught in my early days to say my personal prayers. While I am sure that during those early years I would have prayed out loud, I don't remember doing so. In fact I do not have a single memory of ever offering a personal prayer out loud in my entire life. I have prayed out loud when part of a group, and it has never felt weird, but not when just by myself. As far I can remember I have always offered my personal prayers silently.
While there is nothing wrong with praying silently, the scriptures teach us that we should attempt to pray vocally whenever possible and appropriate. I wanted to try doing so but for a long time did not have the opportunity because I was never alone. So when the opportunity came I ventured an attempt. Since then I have found a few more opportunities to do the same in the last few months. There is progress but I'm still not completely comfortable with it. I don't foresee me having too many opportunities in the future for practice, so I suppose a goal of improving my ability and comfort with vocal personal prayer will have to remain by nature of the long term type.
I have always used the proper respectful language when praying, but for some reason when praying silently I feel as though I am addressing my Heavenly Father who I am familiar with, who in the context of a private communication, doesn't stand on ceremony, while still commanding due respect. When I try to pray out loud it feels as though I am addressing Him in a more formal situation, where my words may be judged and analyzed by others. This has had the effect of producing short and to the point prayers in my vocal attempts, whereas my silent prayers maybe tend to get a bit more windy as I feel more secure about pouring out my heart.
I suppose the important thing is that, whether vocally or silently, we take time to frequently communicate with our Heavenly Father in personal prayer.