There’s a misconception that everyone at Second Skin loves quiet, that we’re all hermits that sit in a padded room reading Charles Dickens novels with earplugs in because we hate sound.
How Sound Works
When broken down in the most simple terms, sound is the energy that is transmitted as vibrations through a medium (solids, liquids, gases). The energy from these vibrations travels as sound waves. When sound reaches our ears we perceive the energy through interpretation by our brain. A yell is the result of your vocal cords vibrating. A loud bang is a vibration caused by two objects colliding.
We like to categorize sound as either structural noise or airborne noise. Structural noise is heard when an object makes contact with another, for example, footsteps, knocking on a door, or rattling parts in a vehicle. Airborne noise is sound that travels through the air, such as people talking, dogs barking, or the radio playing.
There are different soundproofing techniques for the different types of sound you are trying to effectively reduce, and we use all sorts of verbs to describe the specific strategy used to stop the sound waves – a partial list includes deadening, sound absorption, sound isolation, vibration damping, sound blocking. It can get confusing if you’re not familiar with the nuance of what each term means! A good place to start is to understand how sound travels and how to treat all types of noise you might be affected by.
Airborne Noise
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Impact Noise
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Basics of Soundproofing
Not everything advertised as a soundproofing material is going to do a good job at blocking sound. The following three key components outline the most important elements of soundproofing products. If you know to look for these three factors, you will have a huge leg up on identifying if a material will be effective at blocking sound.
Mass
Denser objects with more mass will block more sound. There’s a simple rule of thumb called the “mass law”: every time you double the weight of a material, you improve theSTC ratingby about 5 points. We know this intuitively, because concrete blocks more sound than cardboard. Because you have to double the thickness to double the weight, mass law is subject to diminishing returns. At some point, doubling the material isn’t worth it and we need to build a more complex sound barrier!
Limpness
Although the density of an object is beneficial for soundproofing, you don’t want the product to be stiff. The bending stiffness and internal damping of a barrier affect how well a material can block sound. A limper material such as mass loaded vinyl is better at blocking sound than a hard and stiff one, like steel. Imagine dropping a coin on a metal table vs dropping a coin on a rubber mat. The limpness of the rubber dissipates the energy of the coin and stops the vibrations.
Airtight
The final key factor for soundproofing materials is the airtight seal. Sound is always looking for a weak point, and will easily find small gaps to travel through. This means that even if the area you are trying to soundproof has a lot of mass and is not too stiff, any gaps where the sound will create a flanking path allowing the noise to travel around the material through those air gaps. Sealing up these gaps will prevent the noise from penetrating your barrier.
Difference Between Soundproofing and Acoustics
Although at first glance they may seem like the same thing, soundproofing and acoustics are two very distinct concepts. You will commonly come across a lot of information about acoustics when researching soundproofing, and vice versa, so it is important to understand the difference between the two.
Soundproofing
- Stop sound from transferring between spaces
- Dense, airtight barriers; Isolating physical structures
- Stop sound from transferring between spaces
If you are wanting to prevent sound from traveling from one area to another, soundproofing products are what you need to be looking at. If the material is not dense and able to be installed in an airtight manner, you are not looking at soundproofing material.
Acoustics
- Control reverb inside a space
- Absorption (foam, fibrous); Diffusion to strategically scatter
- Improved sound quality and modestly quieter
If you want to improve the sound quality of a certain room or space by reducing echo and reverb that is being heard, you should be looking at acoustic treatments.
Acoustical materials can help in soundproofing projects because they absorb sound and reduce the amount of reflected noise that is bouncing around the room.
Acoustical materials can help in soundproofing projects because they absorb sound and reduce the amount of noise that is reflected into the room. Adding more absorption to a room will decrease the overall noise level by a marginal amount, but you will still hear all those external noises. Acoustic materials do not block sound. Open cell foam is an example of a popular acoustic material that is useless when it comes to soundproofing, but often marketed as soundproofing material. The product is spongy and porous which is very helpful for absorbing sound, but that absorption is only going to be helpful for reducing reverb and echo already inside the room. If you plan to soundproof a room, you need soundproofing materials to keep the sound out.
Let’s repeat that again in it’s own paragraph to be SUPER clear.
Just because the foam is labeled as "soundproofing foam” does not mean it will soundproof anything. Foam lacks the density to be a soundproofing product, and will not stop sound from transferring between two spaces. The seller is probably labeling the foam that way because they know customers search for “soundproof foam.” It's also possible they just don’t understand soundproofing. The product is “acoustic foam”, because it's designed to absorb reflected sound inside a space.
Acoustic foam can be used as a sound absorbing product, and there are two main categories.One category is melamine foam and the other is polyurethane foam.
Melamine foam
Melamine foam is all made in Europe, and can be treated for fire resistance, water resistance, and other enhancements to give it pretty awesome acoustical and thermal properties. We love using hydrophobic melamine foam in vehicles (cars, buses, trains, planes), as our Mega Zorbe line is aerospace approved and used by companies like Boeing.
Polyurethane foam
We avoid this foam, because it is extremely flammable (not Class A fire rated) and cannot be used in most commercial building applications. The cheap stuff you see on Amazon is made overseas by companies that the US legal system couldn't hold accountable for burning a building down. It's typically sold to residential consumers who don’t know better and don’t have to worry about a fire marshal telling them to remove it.
Instead, we offer a variety of sound dampening panels that can be used in a variety of different spaces.These panels are more durable and better looking, while still performing well in terms of sound absorption.
