In much of writing and writing criticism there's this elusive nebulous thing called "voice". Reading the many writer/agent/editor blogs, there's a lot of reference to "voice" but little definition. There's also a much parroted opinion that nothing else matters besides "strong characters", toss plot, toss narrative, toss ideas, themes, concepts, etc... unless you don't have strong character readers can relate to, enhanced by your own personal voice , you're going to get rejected and everyone's going to hate your stuff. Beginning writers, go off into the wilderness and find your voice!!!
This may be true for the Literary Fiction adherents, but for genre, this notion differs quite a bit.
I like to think things are more complicated than that sort of rote advice. For starters it depends on what you're writing, and who you're writing for.... One easy place to start with the concept of "voice" is to replace the noun with "style." One reason "voice" gets substituted instead of style is that, in my humble opinion, there's a lot of first-person narrative novels in certain genres that get a lot more publicity than others. And when you're getting a chapter of witty sassy saucy Bridget Jones in Bridget Jones' Diary, the "voice" of the writer is obvious. But when you write in multiple viewpoint third person, the "voice" comes down to "style" and is much more difficult to characterize.
Having written one novel in first person, and two and three-quarters novels in third person, I would say establishing voice in the former is a lot easier than in the latter. So how would I describe my voice/style? That's a challenging question, and why I believe its more of an organic process that evolves out of influence and what you find works and what doesn't writing-wise. The marching order "go forth and find your voice!" is in my opinion unhelpful writing advice, despite certain agents/editors craven adherence to demanding authors with a "unique voice". It's a bit of Macguffin.
I write science fiction and while very conscious of character, I will admit "strong characters" is my weakness, but again, my favorite books and novels -my influences- have characters that are more established by circumstance than background. Case in William Gibson's Neuromancer, while loosely defined, is unapologetically two-dimensional. But Gibson's voice was his style, and as the seminal work of cyberpunk, he established a pithy street sensibility spiked with its own lingo and futuristic edge that worked outside its main character. Philip K Dick, one of my favorite authors, has novels filled with interchangeable characters that in themselves are not very memorable, but as representatives of the human condition, fit the everyman role that makes the novels work as a whole. You are Joe Chip in Ubik, you are Decker in Do Androids Dream of Electric Sheep, what they look like, their nuanced mannerisms, their "fatal flaw"... less important as the idea as a whole, per se... I'm not making excuses, but my intention isn't to write the next Holden Caufield (which much to JD Salinger's credit, wasn't his intention either, ergo no "Catcher in The Rye 2: I Hate College Phonies Too."), it's to perfect and make more interesting the concepts and ideas I find interesting.
My voice is my style, and my style emulates more of the sensibilities of my influences than a first-person tone, although depending, that may evolve with the next project.