Speaker

Speakers of the Black Hand are second to only one - the Listener. In Oblivion, the Black Hand is compared to an actual hand, the four fingers including the Speakers and the thumb being the Listener - who gives orders to Speakers who give order to their Silencer s.

Dead Drop Orders
Throughout the Dark Brotherhood questline, you advance in rank only to become Lucien Lachance's Silencer, to which you gain "Dead Drop" orders. The last orders are fake, and you kill the Speakers. In later quests, you become the Listener (after meeting with the Night Mother).