As the fire burns, what is the voice announcing?
It is not completely clear to me what you mean. As the fire burns in the hearth (where it is supposed to) the house is reciting a poem. While the whole house is burning down, the voices did a lot of things, including reciting poetry and announcing the time of day.
But at the end of the story, the voice is making an announcement (but there is no fire at that point). I think that is probably what you are talking about -- at the end of the story, after the house has burned down, the one wall that still stood was announcing the date -- it was August 5, 2026.
The fire is burning at several points when the voice is announcing something. See the quotes below from the story for which answer you need:
1. When the Sara Teasdale poem is recited, "the fire burned on the stone hearth."
2. As the fire overtakes the house, "the voices wailed Fire, fire, run, run, like a tragic nursery rhyme, a dozen voices, high, low, like children dying in a forest, alone, alone."
3. As the house stands in ruins from the fire, the voice announces "Today is August 5, 2026, today is August 5, 2006, today is..."