Prophecy & the sons of No’ach
Ibn Ezra and Radak say that the sons were addressed as well as their father because they had prophetic capacity. Ramban disagrees that the sons were directly addressed and prefers to think that God spoke to them through their father, since the sons had not yet reached prophetic level.
The concept of prophecy developed over time. In the early days it meant receptivity to the Divine voice whilst later, in the days of Moses and subsequently the great preaching prophets, prophecy became the art of articulating the Heavenly message.