If you are a serious writer, you will know what I mean by 'voice'. It seems elusive and nebulous, but I've found it really isn't that hard to understand or to find. The problem most writers have is with quality.
Your writing voice is how you put your words together. All of us who use language to communicate (and I suspect that Dolphins and Wales may be among those numbers) speak in a unique way. Speaking is very natural and we are programmed to learn it as children. Each of us speaks with a unique voice. We adopt slang from our generation or from generations we associate with. We use words common to our environment and we learn how to say things in a certain way by those we have around as our language skills develop. Usually our parents and siblings, who are around us constantly in our first years, are the most influential, but as can be seen from people who grow up speaking multiple languages, school and society are equally important.
All this goes into creating the way we speak. The way we tell stories, such as how our day went, what the dog did with our homework, or to regale an audience with our summer exploits. We have a unique voice even if we are illiterate.
Many people make the great mistake in thinking that writing is our primary form of communications. Writing is just a series of symbols that encode our spoken language into a tangible form that we can share with others. It has recorded the words spoken by others for thousands of years. We can learn how they spoke because for most of human history there was no difference between the written voice and the spoken voice.
Fast forward to modern times. Experts on writing are looking for this mystical thing called 'voice' and can't pin down what it is. Some say you either have it or don't. Some say you can learn it or develop it. Some say everyone has it, it's just a matter of quality. Well, they are all true to some extent. Our modern society has divorced speaking and writing, turning them into two distinct methods of communication. Writing has gained this mythic status as something you have to have talent at. Rubbish! Far too many writers out there make writing far more complicated that it really is and they really want others to believe it is that hard. For the most part they have succeeded, but it is all hogwash.
Writing is speaking through a pen or keyboard. That is all. Just put the words on paper as you would speak them. Too often we get caught in the mystique of writing and forget its origins. For some, this will not result in grammatically acceptable writing, but that is something easy to correct. Good grammar is important for verbal and written communication to maximize your audience. As a society we are far more accepting of oddities in verbal communication then written communication. So that is a concession we have to make. Still, your writer's voice is not some mystical thing, it is the ability to imprint your writing with your unique personality.
I discovered this by accident many years ago when I was tutoring a foreign student in college. She had a paper to write and knew the material very well. But her mistake was to compose it in her native language and then translate it to English. I made her tell me what her idea was verbally and then made her write down what she had just said. The result was an A on the paper. Writers too often try to compose their words and then translate it to the page. The secret is to write it as you would say it. If you have seen the commercials for Dragon Naturally Speaking, there's another example. The people in the commercial go on and on about how it helps make writing easier. Why? Because speech recognition software records your spoken word in text. It bypasses all that translation from thought to speech to writing. If you want to find your writers voice, learn how to speak on the page instead of translating your thoughts into what you think writing should be. You'll get in your own way and obscure your natural voice.
That isn't to say you have the ability to tell a story. That is a different talent only distantly related to your ability to string words together. But it is your ability to string words together that is the key to voice when you write. It puts YOU on the page so that readers can hear your voice when they read your writing. And even the experts tacitly acknowledge this. One of the many ways suggested to improve your writing is to read it aloud. If you follow my advice, when you do that it will flow naturally. Better to have it sound right from the beginning rather than try to fix it at the end. That makes more work and creates and inferior product to what you could have had in the beginning. The closer your rough draft is to your final draft, the more alive it will be. The more it will sing with your own unique voice in every sentence.