During a recent episode of Dr. Phil, there was a Dr. Charles Sophy who is a child psychologist who states that even screaming in front of children is child abuse.
Each state has its own statutes that dictate their own definition of child abuse, but generally speaking a professional is highly regarded by most courts and frequently their opinions can cross state boundaries. For example, I have seen the work or opinions of forensic psychologists, who are considered expert in their field, highly regarded and used by courts even in questionable circumstances.
So by extension, is there some definitive research available that indicates the psychological boundaries of what could be considered child abuse?