Use Acoustic Panels On The Door
They come in a range of materials, from the most popular — foam — to solid wood. They reduce the amplitude of the sound waves that pass through them, effectively soundproofing your door. You can nail them to the door, or to avoid damaging the door, you can use adhesive strips.
Acoustic Steel Doors are an essential element to acoustically treating a space that requires excellent soundproofing. Soundproof Windows' Acoustic Steel Doors have the highest STC rating of any 1.75″ thick acoustical door in the industry.
To soundproof a door, install a door sweep to block sound from coming through the gap under the door. Cover the door itself with acoustic foam tiles, sound-dampening drapes, or mass loaded vinyl to block out sound. You can also paint the door with sound-absorbing paint to reduce how much noise comes through.
Doors play an integral role in controlling the movement of sound through a house. They are typically the thinnest barrier in a wall and, when it comes to blocking sound or reducing noise, they don't benefit from the thicker—sometimes insulated—construction of walls.
Fiberglass doors have some type of foam at their core, which gives them the opportunity to be extremely well-insulated and one of the best soundproof door options if the foam is high-density.
How much do soundproof doors cost? Soundproof doors are expensive and can cost between $1000 and $4000. However, solid core doors are comparatively cheaper and very useful for soundproofing.
Foam does not work effectively for soundproofing as it has insubstantial mass to BLOCK sound whereas it is highly capable of ABSORBING sound. That is why 'acoustic foam' is for real and 'soundproof foam' is a myth.
You can choose either clear standard toughened glass models with 8mm thickness, or go for frosted laminated safety glass of 9mm in thickness. Depending on the type of glazing designs you select, this will dictate the level of soundproofing you have in place.
While there are plenty of ways to add mass, some more effective than others, it's going to be impossible to completely soundproof a hollow door. This is because you're affected by the gap around the door, the frame, and the materials they're made from.
1. Acoustic Foam. Acoustic foam is undoubtedly the most widely known and used sound-absorbing material.
In fact, using blankets is, without a doubt, one of the easiest and most affordable ways to soundproof a room. Even a regular blanket should help reduce echo and absorb noise. As long as it's thick and dense, a blanket could be put anywhere – walls, windows, and doors.
In general, soft, pliable, or porous materials (like cloths) serve as good acoustic insulators - absorbing most sound, whereas dense, hard, impenetrable materials (such as metals) reflect most. How well a room absorbs sound is quantified by the effective absorption area of the walls, also named total absorption area.
Rubber is an effective sound treatment
Rubber has sound absorbent qualities. It can soundproof your room by adding mass to prevent sound waves from escaping a wall, ceiling, or floor. Many schools, hospitals, studios, gyms, and kitchens that need acoustic flooring material, opt for rubber flooring.
So, can bubble wrap be used for soundproofing? Bubble wrap is not a good idea for soundproofing a room, mainly because it doesn't have enough mass. The air pockets in bubble wrap might offer the tiniest amount of sound reduction, but the upkeep and replacement make it not worth the hassle.
Solid oak doors are excellent for soundproofing.
Try a few felt pads.
Just stick a few small felt pads along the edge of the doorframe: Position a pad at the top and bottom of the frame, along with two more pads at the top and bottom of the strike plate. The pads provide just enough soft cushioning to slow down the door as it closes, preventing a slam.
Overall, this door sweep will reduce the level of noise inside of a room, as long as the rest of the door is also secure. However, since the EPDM rubber is fairly stiff, it may make scraping noises as you move the door.