Why are the novel and the movie named The Silence of the Lambs?

The novel, The Silence of the Lambs, by Thomas Harris, and the film adaptation tell the story of Clarice Starling and her investigation of a series of murders. Throughout the story, Clarice visits with the famous serial killer Hannibal Lecter- who is the main character in several other of Harris' works. Clarice recognizes Lecter's intelligence and despite his criminal status, hopes that his work as a forensic psychiatrist can be of some help in her...

The novel, The Silence of the Lambs, by Thomas Harris, and the film adaptation tell the story of Clarice Starling and her investigation of a series of murders. Throughout the story, Clarice visits with the famous serial killer Hannibal Lecter- who is the main character in several other of Harris' works. Clarice recognizes Lecter's intelligence and despite his criminal status, hopes that his work as a forensic psychiatrist can be of some help in her current, perplexing case.

Both the book and film earn their title from some events in Clarice's childhood. After her father's death, she went to live on her uncle's farm and was traumatized by the sounds of the slaughter of lambs. During the duration of the story, Lecter references this part of her childhood with a double meaning. In a letter, he asks her if the lambs have stopped screaming yet. This question may be interpreted two ways. First, Lecter may be asking whether Starling feels she has recovered  from her childhood traumas. An alternate interpretation may be that Lecter is asking whether Starling has any real power in her job as an FBI agent, as she was able to rescue a potential victim from "slaughter" by a serial killer.