Why do empty bottles vibrate when they are inverted?

Because the sound of pouring water changes with the amount of water, the tone becomes higher and higher with more water, because the air in the gallbladder vibrates when pouring water, and the tone becomes higher and higher without air.

At the same time, when the bottle mouth is close to the ear, you will hear the sound of air flow and a lot of air friction in a very small distance between the bottle mouth and the ear, because the air in the container will enter from the mouth and be discharged from the mouth. If you put your ears on the mouth of the container, the air friction will naturally increase. If you bend or bend your palm, you can lean on your ear. The effect is the same.