Every piece of writing has a voice. Even if the writing is written in the third-person, that writing has a voice. The reader can hear the timber of it. The reader becomes familiar with it. The voice becomes as real to them as a voice in a conversation does.
Finding that voice is no easy feat for the writer. It can only be found by writing and writing some more. It only can be discovered by listening to one’s readers. A particular voice may be the correct choice for one audience but not for another. Perhaps the voice needs to change somewhat in order to reach another audience. Maybe the writer needs to evaluate who comprises his or her audience. If an audience isn’t receptive to the writer’s voice, it could be that the writer simply is speaking to the wrong audience. Then again, it could be an issue with the writer. Maybe the writer doesn’t offer the readers predictability. Maybe he or she doesn’t respect the readers.
The question of voice also is determined by subject matter. For instance, a journal article requires a more formal tone and structure. Business writing, too, has its own rules and regulations regarding voice. That doesn’t mean the voice is non-existent; rather, it is cloaked in a different manner. The voice is still there. It is making its point, even if it is doing so via a well-placed semicolon and a conjunctive adverb such as “however.”