There is always the sound of furniture being dragged upstairs at night, and I live on the top floor

It is the building material du in the sandwich layer of the building and the building, as long as the steel is loose, slightly dao

Caused by shaking.

Sometimes back. It's the sound of marbles falling to the ground, sometimes it's like the sound of a chair being dragged How many possibilities are there? First, after learning middle school physics, we all know that objects have their natural frequencies, but in the daytime, the sound is noisy, there are many sound waves or other vibrations, some of which are the same as their frequencies, and some are different, so there will be resonance (resonance is a phenomenon in which the external frequency is close to the natural frequency of the object, and the amplitude is strengthened), forced vibration (the vibration of the object under the action of external forces, including sound), etc. And sound waves still exist, due to the frequency of the object, the frequency of the sound is different, the object has a weak movement (you can also consider the movement of the earth, gravitational force and other factors), there is friction between the objects, there is a frequency, there is a very small decibel sound, people may not be able to hear, in addition to the sound during the day, we can not hear it during the day, but many objects emit a small decibel sound accumulation is large, and the night is very quiet, so it may be heard

Second, the wooden furniture is wet due to moisture in the air or other reasons, but the furniture is dry, and it may make a sound, and at night, it will be heard again

Thirdly, solids such as the earth floor are good mediums for the propagation of sound waves (the medium of propagating waves), and sounds from other places are heard

I think that's about it, and then I think of adding.

Some are indeed the problem of aging buildings, but they can only be heard at night, and what can be heard during the day is deliberately done by people, or you offend your neighbor because of a little power, maybe another neighbor offended a neighbor, you are just lying down and shot, when you go to find them or they use the collision to kill you to deal with you, you can go to the neighborhood committee after the property reaction is not good, if it doesn't work, you will report 110, if it doesn't work, you will and mention their door, if they call the police, you can not admit it, Because the police will understand it after understanding, and in the end you will silently reach a wordless agreement, he will not make a sound, and you will not go to deliver food to his house.

It may be caused by the vibration of the water pipe, but if you listen closely, it really looks like.

I seem to have heard my friend say that, too.

There is the sound of moving furniture and marbles falling to the ground every day in my house, it's okay, ignore it.