why hadnt atticus or any of the neighbors heard the children yelling

Atticus was listening to the radio, and the neighbors were presumed to have been doing the same.

“Just a minute, Scout,” said Mr. Tate. “Mr. Finch, did you hear them?”

Atticus said he didn’t. He had the radio on. Aunt Alexandra had hers going in her bedroom. He remembered because she told him to turn his down a bit so she could hear hers. Atticus smiled. “I always play a radio too loud.”

“I wonder if the neighbors heard anything…” said Mr. Tate.

“I doubt it, Heck. Most of them listen to their radios or go to bed with the chickens. Maudie Atkinson may have been up, but I doubt it.”