All of us are surrounded by different types of sounds we hear every day. Although some of these sounds do not seem to cause much of a hindrance, some can be a nuisance. The constant drilling sound from a nearby workstation, noises from a music studio, and the vehicle honks from the street nearby are a few examples of sounds we can do without. You, of course, cannot go every day and request the concerned person to stop these noises or sounds.
This is where soundproofing materials come into play. Depending on the material, they can reduce or block the sound. Since sound is basically waves, it can reflect, refract, and move around the edges of a material. The soundproofing materials are made with this in mind. Even if the sound cannot be blocked entirely, it can be reduced to a great extent. This method of blocking or reducing the sound is known as soundproofing. You will learn more about this in the upcoming sections of this article.
What are the Different Types of Noise?
Before diving deep into the different types of soundproofing materials, you need to know what the different types of noises are. Primarily there are two different types of noise, and knowing which kind of noise you are dealing with will help you in effectively picking the right soundproofing material.
1. Airborne Noise
When any object or person makes any kind of noise, vibrational energy gets generated. Before these vibrations get collided with a wall or an object, they first get picked up by air or other medium. This noise causes the wall or an object to vibrate, which is how it gets heard in the adjoining area. A few examples of airborne noise include a person speaking, music playing, or the TV running.
2. Structure-borne/Impact Noise
This kind of noise occurs when any object comes into contact with a wall, floor, or any other similar surface with force. When this collision with impact occurs between an object and a surface, the vibrational energy generated by the noise travels to the adjoining areas through the structure. A few examples of a structure-borne or impact noise are a person walking in heels on the floor above yours or a kid bouncing off a ball on a shared wall.
What are the Principles/Methods of Sound-Deadening Materials?
Soundproofing basically involves preventing sound waves from passing through structures. You can understand this better by going through the key principles of soundproofing materials.
1. Deflection
You can deflect sound by adding density or mass to any type of structure like a ceiling, wall, or floor. When solid, heavy, thick and dense materials are used between the sound and the source, the sound waves would have to travel through the bulk, which can help in soundproofing. You can increase the bulk of a wall with the help of concrete.
Deflection of sound with dense and bulky materials is good when you need soundproofing against noises like music. However, it is not so effective when used for blocking impact noises since that involves greater pressure, power, and vibration. Deflection is the key principle of blocking transmission noises.
2. Absorption
The absorption principle is used when the soundproofing is provided by a type of open-cell woven material. Such materials are available in varying densities and thicknesses. These materials are generally used in open cavities where there is a tolerance for material depth. When the cavity is filled, the additional reverberation, resonation, and amplification of sound waves can be prevented.
3. Decoupling
Decoupling involves reducing the direct mechanical linkage area between the structure or substrate. By decoupling, the sound vibrations traveling from one side of the structure to the other side can be interrupted. Soundproofing can be achieved by decoupling the internal structure, like making a ‘room in a room’ or ‘a cell inside a cell’. Decoupling can also be by resilient channels or counterbattening.
A few ways to decouple drywall from a building’s structure include using acoustic hangers, acoustic brackets, or resilient channels. This reduces the acoustic vibration’s strength which in turn reduces the potential of it passing through the wall. The construction stage is the best stage to carry out decoupling.
4. Thermal Conversion
Thermal conversion uses a membrane that converts sound energy to thermal energy. When the sound comes into contact with such a membrane, the molecules in the membrane vibrate and create friction which generates heat. The heat generated is in trace amounts and dissipates through the material from the sides. Such a membrane is about 3 mm thick, and its performance is superior in soundproofing. Although this material is flexible and dense, its acoustic performance is independent of these characteristics.
5. Constrained Layer Damping
This principle involves reducing the structure’s natural frequency of resonation with the help of specific materials in specific ratios. This results in the reduction of flanking transmission from one to the other side of the structure.
Constrained layer damping is very effective when damping compounds are placed amidst two rigid panels. When sound hits such a structure, friction gets created in the damping layer due to the shearing forces acting between the panels. This would convert the sound waves to heat. This is perfect for reducing noises of low frequency.
What are the Types of Sound-Deadening Materials?
There are a variety of soundproofing materials that you can choose from depending on the application. Each of them works on either of the principles mentioned above and is best suited for a specific type of application. This section will talk about the different sound-deadening materials and their uses.
1. Polyurethane Foams
Polyurethane foams or acoustic foams have open cells that are a result of gas bubbles that have popped. Air can easily go through such foams. The sound waves create pressure in the foam within the porous areas. This creates elastic stress waves that are carried through the material. Since polyurethane foams are open-cell, porous, and flexible, sound energy gets diminished within it easily.
Such foams are very good for providing soundproofing against high-frequency sounds. The porous build of this material decreases acoustic reflection to a great extent. Although acoustic foams are chemically inert, they are flammable. Due to this reason, polyurethane foams are not suitable for industries.
2. Felt
Felt is a material that is created by matting and pressing fibres together. The fibers used in such material may be synthetic, natural, or a combination. Felt maintains its properties even in the presence of lubricating oils, moisture, salts, greases, and detergents and is also chemically inert. It can easily bend in an uneven surface which prevents unwanted foreign substances from entering the load-bearing region.
Since it is made of multiple fibers, it is extremely resilient. With an optimum density level and spring, felt offers very good sound absorption. The sound waves get absorbed by the individual fibers in felt. These sound waves are then converted to heat energy by friction. With these qualities, felt is the best choice in industrial setups and also a damper in musical instruments.
3. Polyester Fiber
Polyester fiber is made with a long chain of synthetic polymers. They usually are used either in a non-woven or woven form. Polyester fibers are used to make lightweight and non-toxic insulation materials. It is used as a soundproofing material due to the optimum balance of density and porosity it possesses.
Polyester fiber is very effective as a soundproofing material against high-frequency sound waves. Properties like excellent tensile strength, abrasion resistance, impact and wear resistance make it an ideal soundproofing material in industries with heavy machinery.
4. Fiberglass
With the desirable qualities of light weightness and rigidity, acoustic fiberglass is an excellent soundproofing material. This material can be customized as per your need to fit into even the tightest of spaces. Acoustic fiberglass is generally used in halls and rooms where echoes and reverberations must be limited.
5. Mass Loaded Vinyl
Mass-loaded vinyl is made up of a viscoelastic material and an inert material. The property of viscoelastic materials to go back into its original shape once force is removed, attributes to its ability to act as a soundproofing material. Basically, this material acts as a tuned damper which reduces the frequency of sound waves.
When exposed to very low temperatures, vinyl becomes hard and compliant when subjected to high temperatures. In both cases, it won’t be able to limit sound waves effectively. To avoid this, plasticizers can be used so that this material acts appropriately at different temperatures. Although this material is suitable for areas with many bends and corners, it is not the first choice since it is expensive.
6. Cork
You can use cork if you want a natural way to soundproof an area. This material is elastic, fire-resistant, and significantly impermeable. It is so good as a soundproofing material that even with a thickness of 3 mm, it can block almost 10 decibels of sound. This is because cork is made up of 50% air which is a great insulation material. The cells in the cork are arranged in a honeycomb manner, and when sound energy passes through them, it gets converted into vibrational energy.
7. Green Glue
This is a type of viscoelastic material that has a constrained layer-damping system that insulates sound. This green glue is generally sandwiched between two rigid surfaces. When the sound waves hit this rigid material, it starts shifting in different directions resulting in shear forces inside the green glue. The polymer in the green glue converts this shear energy to friction and, ultimately, to heat. Green glue is a non-toxic material, but just as its name suggests, it majorly acts as an adhesive between rigid layers.
8. Silicone
Silicone is an excellent choice for soundproofing small spaces and corners as it provides air-tight insulation. It has multiple desirable properties, including highly inert, low thermal conductivity, water resistant, and UV-resistant. In several applications, it is applied in a paste form before getting cured and getting a rubbery texture. Such a coating is airproof and is effective in stopping sound propagation by air. It is best for damping mid-frequency sound waves.
9. Epoxy
Epoxy’s damping properties and air resistance make it an excellent soundproofing material. It is generally used in combination with other soundproofing materials. Epoxy is much superior to regular glues. This makes it pretty useful as an adhesive while setting up soundproofing materials. In some cases, epoxy can also be applied as a coating for soundproofing.
10. Floor Underlayment
To reduce sound transmission between hardwoods and engineered floors, floor underlayments are a great option.
11. Acoustic Panels
Acoustic panels come in a variety of types, styles and colors. They look incredibly appealing when installed in any space. They can be mounted on walls or ceilings to reduce sound reflections and reverberations. It is ideal for cinemas, recording studios, game rooms, and other entertainment areas.
12. Acoustic Caulk
Acoustic caulk is similar to regular caulk and blocks the air by tightly sealing the gaps in walls, windows, and doors. Its superior noise-blocking properties can also be used to stop sound vibrations. It is best suited for sealing the cracks in doors, window frames, ceilings, and walls.
13. Acoustic Window Inserts
Acoustic window inserts are used to seal the already existing windows tightly. It is made using high-grade acrylic. This is why it is really good for reducing and absorbing sound. They are good for both historic as well as single-pane windows. Although you can use this with double-pane windows, noise reduction will be very less.
14. Acoustic Floor Tiles
Acoustic floor tiles can be used to absorb the sound waves that get generated due to impact. It can also be used for soundproofing against noises from nearby sources. They are ideal for soundproofing rooms that echo.
15. Exterior Sound Absorber
Exterior sound absorber is a type of acoustic barrier specifically for exterior spaces. It can be used to effectively block noises and sounds coming from outside. The exterior sound absorber needs to be placed at the right height and angle for maximum effect.
Such an exterior sound absorber can block the noise from traffic, trains, and neighboring plots. Installing an exterior sound absorber like an acoustic fence is pretty easy, quick, and effortless, making it the most preferred choice for soundproofing residential areas.
16. Mineral Wool
Mineral wool is an open-cell insulator that absorbs thermal and acoustic energies very well. It can be commonly seen being used as stud walls. This rigid material comes in varying densities and thicknesses and is used in commercial and household projects.
This affordable material is used for soundproofing ceilings and walls. It is used to make bass traps and acoustic panels. Mineral wool is a natural soundproofing material that is moisture and fire-resistant. Although mineral wool is great for reducing sound, you must use a very thick layer to get effective noise cancellation.
17. Sound Deadening Spray
Sound-deadening spray is mainly used for spot treatment. For instance, a floor mat may be installed to reduce noise, but there may be gaps between the floor mat and the adjacent surface that allow some of the noise to travel. The sound-deadening sprays can be used to minimize these kinds of gaps which would improve the overall acoustic performance greatly. It is very easy to apply and is pretty effective. Such sprays are mainly used in car boots, doors, and compartments.
18. Sound Deadening Paint
Sound-deadening paint does just as its name suggests. It can be applied using a roller, or it can even be sprayed on the required surface. As the thickness of the paint increases, so does its effectiveness. The recommended application method is spraying the paint as it results in a much thicker paint layer.
Although it is not a great sound-deadening material, it is definitely a better alternative to water-based paints. This paint contains latex which settles into cracks and provides decent noise cancellation. All in all it is an affordable option to reduce sound transmission through walls.
19. Acoustic Plaster
Acoustic plaster contains various systems and compounds that can decrease or increase the flexibility and weight of the material. This would substantially decrease the surface reflections, which would help in internal acoustics equalization. The applications of acoustic plaster can be majorly seen in restaurants, theater, entrance halls, universities, and museums.
20. Acoustic Sealant
Acoustic sealants are majorly used during wall construction where soundproofing is required. Acoustic sealants basically work by dissipating sound vibrations trying to pass through the wall. Such sealants reduce leakage to a great extent and can be used to countersink mechanical fixings heads.
Acoustic sealants are great for covering any holes or gaps like seal holes, seams, and screw holes. It is very easy to apply and is available at quite a reasonable price. Although it is a great eco-friendly soundproofing option and is very effective in its function, acoustic sealants are best used in combination with other soundproofing options.
21. Curtains and Drapes
Soundproof curtains and drapes are used widely for the reduction of noise. It creates a temporary partition in areas like the theatre backstage. When you hang it in some specific positions, it decreases the spread of sound waves from one space to another. It is ideal for soundproofing in bedrooms, nurseries, and home theaters.
Sound Deadening Materials – FAQs
Ans: Regular insulation can reduce sound to an extent. Still, it is definitely not as effective as the special acoustic insulation materials that are particularly designed to block and absorb sound waves.
Ans: Yes, several eco-friendly sound-dampening materials are available like cork panels, cotton insulation, mineral wool, and acoustic wood panels.
Ans: Although sound-dampening materials can significantly reduce the noise or sound, they cannot completely eliminate all noise. If you want complete silence, specific construction techniques and combinations of different materials would be required.
Ans: Yes, sound-dampening materials like outdoor acoustic panels and exterior sound barrier fences are specifically designed for outdoor soundproofing, like reducing traffic noise or noise from a nearby construction site.
Ans: Yes, sound-dampening materials like acoustic panels, bass traps, and diffusers can be used in recording studios to control sound reflections and reduce interference to the minimum.
Conclusion
With the help of this article, you can easily know what soundproofing materials are and their types. You can even understand the principles used for soundproofing from this article. You can now pick the best-suited soundproofing material based on the end application. If you are considering soundproofing your home, recording studio, or office, this article can greatly help you.
