Science actually figured this one out. Beavers raised in captivity when exposed to a speaker playing river noises will cover it up with as much stuff as possible to hide the noise. So it's the noise they have an issue with
They require ponds to live safely. They build dams which create ponds. Then they build little mound houses out of sticks and mud in the middle of the pond. The house only has underwater entrances. They can cut trees down and float them into the pond, where it is safer to eat. They're mostly aquatic mammals.
They have been known to live in lakes, and when they do they dig dens under the shoreline.
The reason they don't like the sound of running water is the same reason we don't like to hear the sound of unexplained running water in our homes, it's a sign of a leak. The only difference is for them it's instinctual, and for us we understand the consequences of a leak in our home.
There is a norwegian study that found that isolated beaver babies start piling up sticks and stuff at some point but do not build dams. They concluded (the scientists) that piling up stuff is genetic and building dams is cultural (has to be learned).
I have no link but the study was made in Bø
Baby animal studies focused on play are always so cool. Like bees appearantly will play with objects that have nothing to do with their survival.
We do the same thing I think. Kids will pile up or mess about with any stuff you give them whether they have a cultural understanding of it's use or not.
Ok so what's the deal with people who rap or sing along with their headphones? I would never have the guts. What is going on with these people? How do they do it?
Covering the noise is covering the running water. Covering the running water creates a dam. Creating a dam creates a pond. Creating a pond provides them with a nice controlled environment in which to build a lodge with an underwater entrance for protection from predators.