Who taught caliban to speak in the tempest?

In Shakespeare's "The Tempest," Caliban is taught to speak by Prospero, who arrives on the island and takes control after being shipwrecked there. Prospero initially teaches Caliban language and communication, hoping to civilize him. However, Caliban later resents this impartation, feeling that it has only led to his subjugation and loss of his natural identity. This relationship highlights themes of colonization and the complexities of power and language.