The Sound and the Fury uses stream of consciousness, a stylistic technique in which the narration follows the direct psychological experience of a character.

The four parts of the novel, each told from the perspective of a different character, all have distinctly different styles. Benjy's section is the most chaotic because of the character's mental limitations. The jumps between the past and present make it difficult to follow, and the fact that he doesn't understand much of what is happening adds to the difficulty, but it allows us to not only experience his unique perspective but also to get a glimpse of things that others' opinions about might skew our reading. The next section, focused on Quentin, follows a more, but not fully, linear development. Quentin's obsession with certain events in the past make every experience a commentary on those memories. The Jason section is the most straight-forward, as Jason is the most practical and materialistic of the family. This makes the narrative style in his part a bit more tricky, though, as his prejudices and anger require readers to make quite a few difficult inferences about what is really going on versus what he wants to believe is going on. The final section, the only one written in a first person point of view, follows Dilsey, a black woman who works for the Compson family. The narration in this section is more poetic and musical than in previous sections, and the focus on Easter and the religious experience, which the character takes very seriously, provides a warmth and sense of redemption much needed after the preceding three sections.

The narrative technique is stream-of-consciousness and it is used, in this novel, to create an astounding effect.

Each character given a chapter is represented in The Sound and the Fury by the workings of his or her mind. Dilsey and Quentin could not be more different as people, a fact which we discover very clearly when we read the chapters written from his and her point of view. Their tendencies, their challenges, their obsessions are all on display in the stream-of-conscious mode.

We can say then that this narrative technique is also a characterization technique.

The narrative technique used by Faulkner is known as stream of consciousness.  This is when we learn each character's perspective directly, with no filter.  We listen to the character's thoughts directly.  Here is a descriptiion

http://en.wikipedia.org/wiki/Stream_of_consciousness_(narrative_mode)

Some readers find this narrative style freeing, because it's like being the character.  Others just find it confusing.