My degree in psychology came before my chartered accountancy designation (for LJ, this includes AICPA).
The study you quote is not like for like. These are stimuli presented to subjects, the topic being short-term memory.
However, we are not talking about short-term noises, words, conversations, random beeps. We are talking about a 'harrowing scream'.
Can you see the difference in impact and proportionality. The aural part of the brain is one of the oldest, right at the back (from memory), which indicates it is a deeply instinctive survival mechanism. A scream from a human, has the same effect as a baying animal or squawking bird warning of the presence of a predator. The autonomous nervous system reaction is one of fear, fight or flight. Ms Capezelli felt the scream through her whole being, as did Amanda, who claims she was reduced to crouching in the kitchen, as did Rudy, who came running out of the bathroom (he claims) with his trousers around his ankles.
Conversely, witnesses do not claim to have heard a 'harrowing scream' unless they did.