The Mage Who was Constantly Called Incompetent was Actually the World's Strongest but was Unaware of It Due to Being Confined

Story:

Born with the gift of Hearing—deemed "useless" by those around him—Ars was imprisoned in a tower by his disappointed parents. But one day, he discovers that his enhanced hearing allows him to replicate any magic spell he hears, even legendary incantations wielded by the gods themselves. In time, Ars rises to become the world’s most powerful mage. Stepping into the outside world, he begins his journey… utterly unaware of the overwhelming power he wields!