The objective of soundproofing materials is to prevent noise from both entering and leaving a space. However those materials come at a cost, and typically the words "cheap" and "soundproofing" don't go together.
Soundproofing can really boil down to your personal goals for the space. If you're on a budget, those goals also need to be realistic.
Before we explore the materials, we'll first discuss methodology and different types of noise.
There are four main methods used when soundproofing a space:
The easiest way to soundproof something is to add mass or density to the object (walls, ceiling, doors, floor, etc). The more dense something is, the harder it is for sound-waves to penetrate it.
Using various widths and densities allows you to reduce sounds within a variable frequency range. However, it's important to note that even heavy walls will still vibrate, just not as easily. You will also still be able to hear low frequencies (bass) easily.
Damping, put simply, is the reduction of resonance in a room through absorption or redirection (reflection or diffusion). In laymen terms, it means to dissipate vibrational energy before it has a chance to build up and radiate as sound.
Sound is nothing more than vibrational energy. Meaning, sound will conduct easily if there is a direct pathway to follow.
Think of this like tin can telephone. As you talk into one can, the vibration conducts through the string and is heard in the other can as sound. However if you were to cut the string or "decouple" the path for sound to travel, there is no where for sound to travel.
Put simply, it is beneficial to decouple the framing and ceiling as it's simple and rather inexpensive.
As you might expect, air cavities will resonate. You can think of this concept like hearing the ocean in a seashell or blowing air across the top of a bottle. Both of these sounds are produced as a result of the trapped air resonating.
In a similar fashion, trapped air in a wall will also resonate. When the wall is vibrated by sound from an adjacent room, the trapped air in the wall also vibrates.
The goal of soundproofing is to attempt to eliminate sound. There are two primary types of sound: airborne and structure-borne.
When a person or object makes a noise, it generates energy in the form of vibrations or sound-waves. These sound waves are picked up by a medium, like air.
The soundwaves will travel through the air until they collide with a solid object or structure like a wall, ceiling, window, etc. The sound then vibrates and is able to be heard in the adjoining space.
Examples of airborne noise include: people talking, music, and the television.
Structure-borne or impact noise occurs when an object collides with another object.
For example, when a ball is bounced against the floor, the impact you're hearing is structure-borne. The ball collides with the floor, and the vibrations travel through the air cavity and through the structure and into the ceiling below.
Let's explore some cheap, cost effective materials that can be used to soundproof a space:
Instead of installing new drywall or insulation (both of which can be quite expensive), you could use sound deadening blankets. The softness and density of these blankets help to slow the passage of soundwaves, thereby minimizing noise.
To use soundproofing blankets, affix them to the surfaces that unwanted noise is traveling through; the walls, door, and even the ceiling.
Use nails, tacks, or affix them to curtain rods.
Soundproof curtains are another inexpensive medium that you can use to cut down on unpleasant noise levels in your home. Like soundproof blankets, these curtains are made of dense materials, which helps to absorb and slow the passage of soundwaves.
Obviously, these curtains are ideal if you’re trying to reduce the levels of noise that are flooding into your home through the windows. They're also a much more budget-friendly option than installing soundproof windows.
You can also use sound deadening curtains to block out undesirable sounds that are coming through the walls or the door of the room. To maximize the soundproofing results, hang two sets of curtains on the surface in question. Purchase and install a double-hung curtain rod and then hang two soundproof curtain panels from the rods.
While wall-to-wall carpet is considered an effective way to cut out noise pollution that travels through ceilings and floors, you could try using area rugs.
The thicker the area rug, the better, as thick area rugs will add more mass to the floor. As we noted above, mass or density is one of the best ways to reduce the passage of soundwaves.
If you have the budget you might consider affixing a layer of soundproofing material like Mass Loaded Vinyl (MLV) to the bottom of the rug.
You might even consider installing floor underlayment. However this does involve removing the floor and then installing the underlayment to the sub-floor.
Believe it or not, the furniture that you already own can be used to minimize sound transmission. There are several ways that you can use your furniture and accessories to soundproof a room.
The concept being applied here is known as Diaphragmatic Absorption. In laymen terms it means that when a sound passes through an object and then collides with the object, soundwaves won't have enough energy to travel back through the diaphragm.
While egg cartons do create a cavity or diaphragm, they don't have a large enough cavity to completely dissipate sound transmission. This is why acoustic foam tiles are an effective medium, as they are a dense material.
We have a full article on this concept that you might consider reading. However, in short, egg cartons do absorb SOME sound energy.
As you can see, there are a number of different materials that are relatively cheap.
However, to reiterate, soundproofing in general is an expensive process. The required materials to effectively soundproof a space are engineered to combat and eliminate sound. These materials are also quite expensive.
The aforementioned materials are a good jumping off point to a quieter space.
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