A child's screams of "No, Daddy" were followed by dull thud sounds interspersed with crying, a court heard.
The sounds came from the home of Simon and Michelle McWilliams, who deny cruelty to a four-year-old boy they were adopting.
College teacher Janet King, who lives next door to them in Gardner Road, Fishersgate, Southwick, was having a morning bath at the time.
She told Lewes Crown Court yesterday: "I heard a child crying hysterically. Then I heard what I assumed was a boy screaming 'no daddy'.
"Then I heard three or four dull thuds with crying in between. I was horrified. I dropped my book."
She saw the couple with the boy, John Smith, and another child the couple were adopting a few days later and everything seemed fine between them. She said they appeared devoted parents.
On another date the McWilliams' other neighbours, Sharon and Paul Howard, told how they heard noises coming from the defendants' house.
It was the day before John died on Christmas Eve, 1999, from a brain haemorrhage. An examination of his body showed he had 54 external bruises and four adult bite marks.
Mrs Howard said she was woken early on December 23 by the sound of banging. It appeared to come from the McWilliams' front bedroom.
She said: "It was like a ball, like a basketball. It lasted for about a minute then it stopped. Then it started again and went on for 30 minutes with breaks in between."
An ambulance arrived to take John to hospital. The boy died the next morning.
The trial continues.
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