Sound travels faster in solids than in air, but it also loses energy more quickly. This is because the molecules in solids are closer together, so they can interact with the sound waves more easily. When sound waves hit a solid surface, some of the energy is absorbed by the surface, and the rest is reflected back into the air. The more energy that is absorbed, the quieter the sound will be.

When you shut a door between two rooms, you are reducing the amount of surface area that sound waves can interact with. This means that more of the sound energy will be absorbed by the door, and less of it will be reflected back into the room. As a result, the room will become quieter.

In addition, the door may also act as a barrier to sound waves. This is because the door is made of a material that is denser than air, and sound waves have a harder time traveling through denser materials. As a result, some of the sound waves may be blocked by the door, which will also contribute to the reduction in noise levels in the room.

Here are some additional factors that can affect how much sound is transmitted through a door:

• The thickness of the door. Thicker doors will absorb more sound energy.

• The material of the door. Doors made of denser materials, such as wood or metal, will absorb more sound energy than doors made of lighter materials, such as plastic.

• The presence of gaps or cracks around the door. Gaps and cracks will allow sound waves to pass through the door, which will reduce the amount of sound absorption.

By taking these factors into account, you can choose a door that will help to reduce noise levels in your home