Why does Bradbury use repetition on p29-30? What is the effect?

I'm sorry, my copy of the story has no page numbers.

Examples of repetition:

“And the uncles, the aunts, the cousins, the nieces, the nephews, that lived in those walls, the gibbering pack of tree apes that said nothing, nothing, nothing and said it loud, loud, loud.”

The voice-clock mourned out the cold hour of a cold morning of a still colder year.