It actually has a rather curious scientific explanation
It can also occur during the day, although it is more common to hear it at night.
Has it not happened to you that you are lying quietly in bed at night and suddenly you hear strange noises on the ceiling? On many occasions it could be described as the sound of marbles rolling on the floor, and sometimes it even has a certain metallic tone.
the logical It would be to think that they are children playing with marbles.although the truth is that this sound can occur even if the neighbors do not have children, since the sound is due to another reason.
Actually the sound is due to an acoustic illusion produced by the pipes in the wallsand that are produced by a phenomenon known as Zhukowski pulse or water hammer.
This sound is produced whenever we close a water tap or a valve or when a washing machine stops catching the water, and this can happen at any time of the day, although it is more frequent that we hear it at night as there is less noise.
Now, what is the scientific explanation behind this event? Well, what happens is that the fluids have an elastic behavior, which causes that when the water flows through the pipes, the drops that were about to come out of the tap stop dead when you close it and that causes those that are further back to end up colliding with those in frontthus causing this sound to be given.
That is why, due to the reverberation of the pipes when the water stops dry, this curious sound is produced. And you have to know that if you hear this sound you don’t have to worrybecause most of the time it is completely normal, although it is true that sometimes it can be directly related to possible faults.