What is the ruling on an individual reciting aloud during prayer, and is he permitted to recite silently?

Reciting aloud in audible prayers is a Sunnah (definition) for the Imam and for the person praying alone. If one recites silently, there is no sin upon him, but he has left the Sunnah. As for the one praying alone, if he finds that silent recitation makes him more submissive, there is no harm, for the Prophet, peace and blessings be upon him, would sometimes recite aloud and sometimes silently in the night prayer. As for the Imam, the Sunnah for him is always to recite aloud, following the example of the Prophet, peace and blessings be upon him, and due to the benefit it provides to the congregation.