I think it's significant that the Shrieking Shack was built specifically for Lupin. Dumbledore didn't take a house that already existed in Hogsmeade and insert a tunnel into Hogwarts from it.
"This house -" Lupin looked miserably around the room, "- the tunnel that leads to it - they were built for my use."
(Prisoner of Azkaban, Chapter 18, Moony, Wormtail, Padfoot and Prongs).
It's stated that the Shack became a site of wild legend, somewhere that locals were afraid to go near. It became known as the most haunted building in Britain. Dumbledore encouraged these rumours.
Yet how would the legend of the Shack develop? The residents of Hogsmeade would've known that the Shack was newly built. They would've seen someone from the school doing the construction work. It wasn't a creepy old building when Lupin attended school. It was a newly finished house on a site with no known history of haunting. With or without the strange noises, how did the haunting story ever get off the ground? It seems implausible to me that people could be scared of a house that they presumably knew was just recently put up by the local school.