How Hosseini uses voice - chapters 16/17

In the start of chapter 16, there is a switch in the narrator; previously in the novel, the narrator has always been Amir, therefore the reader has only seen the narrative from Amir's perspective, however throughout chapter 16 the narrator is Rahim Kahn speaking to Amir, describing his
experiences with Hassan. For the reader, this is a refreshing change, as we finally get to view the perspective of other characters as the soliloquy by Rahim Kahn is sustained enough to give the reader a clear view of his story. By allowing the reader to hear a significant part of the narrative, the story of the adult life of Hassan and his family, from a different character to Amir almost makes the narrative more real and less biased, as we can experience it through various characters eyes. For example, a description of Hassan may have been altered by Amir, as he has a different perspective of him than Rahim Kahn does.
Also in chapter 16, we have direct, attributed speech from Hassan himself, talking to Rahim Kahn; '

"We don't have that much to drop, Rahim Kahn," Hassan said... "Wey'll go with
you..." '

Hossieni allows us to hear Hassans words maybe to give more realism to Hassan's character. We also hear speech from Hassan's mother, and Hassan's son in chapter 16, by doing this Hosseini is creating realistic, believable and effective characters.

In chapter 17 the narrative switches back to Amir, although direct and attributed speech is still heard from both characters to let the reader know the conversation is still in tact. However, we see a letter from Hassan to Amir, which finally allows us to see Hassan's point of view directly, not through Amir or Rahim Kahn's description. Through voice and speech in this chapter, we also find out another significant part of the narrative, that Baba was Hassan's father, making Amir and Hassan half brothers, meaning the reader finds out as Amir does, so we share the feeling of shock.