For some reason in the past few weeks I've run across quite a few references to "omniscient voice" that are incorrect. A couple of these were even in book reviews. The correct term to use would have been multiple third person.
The terms can be confusing because omniscient is a form of third-person--in that it obviously isn't first person. But true omniscient voice sounds very different than the oft-used "close" third person of today. The omniscient voice has a removed quality. It sounds like a god-like narrator sitting above the action, looking down at all the characters. This narrator can see into all characters' minds, but it can also see things a character is unaware of. In a novel written in omniscient voice, this narrator's voice is the most prominent. All scenes are described in this narrator's unique way of talking. It's his word choice, his level of vocabulary, etc. These stories are often more "told" than "shown" since the narrator is telling you, the reader, what is happening in all aspects of the scene.
Omniscient voice was used much more frequently in the classics. Today's more intimate culture (formed by TV and movies and so much more) has led to a more intimate voice form in novels--what is often called "close third person." This is the type of third person in which I write.
In close third person, the reader is fully in the head of one point-of-view character at a time. (Preferably one per scene!) The only more intimate voice is first person. Since the P.O.V. character is "living" the scene, all thoughts, description, and narrative are told in a way that this character would speak and think. You can have a single third POV throughout the book. Most novels have more than one third person POV character. This voice is called "multiple third person."
There is a kind of third person in between close and omniscient. It's a little more removed and formal in tone than close third. Has a little more of a narrative feel. Yet it's not the completely removed tone of omniscient. Omniscient does have a very different tone to it.
If you read a recently written novel with multiple viewpoints, that doesn't mean the book is necessarily written in omniscient voice. Most likely it's not. It's probably multiple third person. We need to be careful of our terminology. Those who understand POV terminology correctly will really be mislead if you erroneously say a book is written in omniscient voice.
If all this isn't quite making sense, come back tomorrow. I'll run a section from one of my books (written in close third), then rewrite it in omniscient voice to show you the difference in tone.