My hard-SF story now has characters and a plot. It also has a voice, although not a particularly distinctive one.
Voice is the way the story is written: diction and sentence construction as much as content. It may be the voice of the character, especially in first person. It may be the habitual style of an author. I can always recognize work by Ursula LeGuin or Karen Fowler from just one paragraph -- sometimes one sentence. And I think I have sometimes achieved and sustained an individual voice, as in "Fountain of Age" or "Beggars in Spain."
But I find it hard to do in hard SF. There is so much technical information to be conveyed, and somehow I can't seem to do it except in straight-forward, serviceable prose. Clear, but neither individual nor lyrical. Furthermore, I think very few writers can. NEUROMANCER has a distinctive, jazzy, unmistakable style -- but Gibson's computer world is mostly fanciful, not realistic. Bruce Sterling, a lesser stylist, is a surer guide to what the future might actually look like.
So my story moves along in a useful but not captivating voice, and I hope that other fictional elements will make up for the lack.