Afaik it was a person who did not live there, who made the call ?
As far as noises, the most practical thing one would think as a student would be people returning from a night out and any cries or yells might be the same , just making undo noise, as in whooping it up ?
One's mind does not immediately go to : "Oh no, someone is in the house -- killing people !".
If they heard something it they might think; "Come on, be quiet, we're trying to sleep...".
Or something similar, and that's sad.
So I can imagine that scenario.
The killer has damaged so many lives.
By all accounts this was a peaceful town, students felt safe, and no one expected such a horrific attack to take place.
M00.