Info Primer: Soundproofing

Soundproofing is not like any other do-it-yourself project:

You could easily waste an enormous amount of money and time if you don’t know exactly what you are doing.  Worse than having little or no effect on sound control, there has been instances wherein some people have spent unforgiving amounts of time and money, only to have the noise that they are trying to block or reduce actually made louder.  Even acoustical engineers only use proven and tested methods when designing a soundproofing solution for any given situation.

First consider your expectations:

There is nearly no such thing as “a completely soundproof room”  or house, office, etc..  Noise travels on different wavelengths.  Thus, completely blocking any wavelength (which is hard enough in itself) would still leave other wavelengths open.  So the word “soundproofing” is actually a misnomer from a practical sense.  However, we will use the word since it is what most persons use (not knowing any better) when looking for this kind of information…

“Old wives remedies,” myths, and nonsense:

The topic of soundproofing probably has the most myths and complete nonsense associated with it than any other topic.  It is amazing how so many people will comment on this topic without any factual evidence or tested experience.  Perhaps on the surface it seems to be a “common sense” type of discussion, and in a few ways it is.  But many of the things some people have remarked or alluded to, however well intentioned – are downright disastrous to sound control efforts.  Some of the common myths and nonsense about soundproofing follow:

  • Egg cartons.  Though there is some evidence to suggest that egg cartons have benefits in sound conditioning, (now key word: “conditioning”) they will do nearly nothing if not completely nothing for soundproofing.  It is one of the most ridiculously silly and out of control rumors on the internet.  Hold an egg carton to your ear between a speaker on your stereo….   Does it do anything?  By sound conditioning, we are referring to something such as a recording studio.  Recording studios sometimes have their walls lined with egg cartons.  This is not for soundproofing, but for sound conditioning only.  The theory related to sound hitting a rigid flat wall, so the egg cartons act something like a “cushion” if you will, from the vibrations hitting the flat rigid walls, causing shrill sounds.

  • Cup Holders.  You know those things you get from fast food restaurants when you order multiple drinks to go…..(Same explanation as above applies)

  • Styrofoam   Absolutely worthless for practical soundproofing, not to mention relatively flammable.

  • Any Foam (for that matter)  Most types of foam are pretty well flammable and wouldn’t pass code inspections.  Most also do little for soundproofing.


The 2 Basic Elements of soundproofing:

  1. The density and mass of building materials.       This deals with the subject of what materials your home, office, or apartment complex is constructed from.  But furthermore, if you add materials in a soundproofing effort.
  2. The relationship of how those materials are joined (if joined).

Generally speaking, it takes more intense or louder noise to cause vibrations in denser materials, and therefore transmit sound through;  And mass is a sound diluter.  So, as a preceptor lets consider that distance is mass.  So let’s say that you are outside and your next door neighbors are blasting their stereo.  Of course you are going to hear it, and possibly get upset from the noise.  But if it was your neighbors 5 doors down, you would probably still hear it, but it possibly wouldn’t be loud enough to bother you much.  And if was two blocks away you probably wouldn’t hear it at all.  And this is all without any materials between you and the source of the noise.  That’s because the more distance, the more mass;  so even the air you breath can stop sound.  Of course, it takes a lot more mass because there is no density to speak of.  So again, generally speaking, the less dense the materials your home, office, etc. is constructed from, the more mass you would need to compensate for soundproofing.

In many instances, the material your place is constructed from would be sufficient to keep it relatively quiet.  That’s right….  Just your external siding, your internal drywall, and the air space between the two would do a pretty fair job of sound control for many situations….  If  it wasn’t for how those materials were joined together.  Because modern construction techniques rigidly join materials together, there is no sound absorption, but rather sound transmittal.  Thus, though your walls have 2 shields for noise, either between rooms (drywall side1 and drywall side 2), or outside to inside wall (aluminum/wood siding to drywall or panel-board etc.) they are rigidly joined together usually by 2X4 boards between with the use of nails or screws.  Therefore, vibrations (i.e. noise) readily pass through.  So, joinery for soundproofing is best achieved by decoupling techniques.  Air gaps are extremely useful between materials because they reduce sound transmission from one material to another.  But there is no air gap from a soundproofing standpoint if a rigid point or points of joinery (i.e. a 2 by 4 board holding 2 drywall boards together with screws or nails.

The All-Time Most Important Soundproofing Tip:

Make the room or whatever you are trying to soundproof… air tight.  Soundproofing professionals have a saying:  “Caulk is cheap.”  So the expert advice is to use it aggressively and liberally.  Caulk every little gap and crack to the point of taking off your electrical, cable, and phone outlet jack covers and caulk filling the gap between the outlet housing to the wall.

The most common reason most do-it-yourselfers fail in their soundproofing project is this one single reason.  Every tiny little hole or crack matters.  If light can go through any tiny crack, sound will definitely go through it.  Also look behind your skirting and trim boards.  You will almost always find large gaps behind such.

  • Also you should consider purchasing acoustical caulk made especially for soundproofing from a soundproofing supply source.  It is one of the few specialty items in any industry that is reasonably priced.  Other kinds of caulk that dry flexible may work fine (but not latex caulk);  In fact other caulks may do just as good of a job.  But why risk something like this when acoustical caulk is about the same price as other kinds of quality caulk?  Whatever the case, the recommendation is not using latex caulk.  And definitely do not use any caulk that dries hard or crusty.  It should dry flexible and resilient.
Specialty soundproofing caulk
  Soundproofing caulk is a specialty item that is reasonably priced compared to other specialty items of other crafts.
Caulked gap at floor for sound proofing
This is under the moldings base line boards. Notice how the wall on the right side of the picture is caulked; while the wall on the left side is not caulked from the floor to the sheet rock. The standard construction method is to NOT caulk like shown on the left side of the picture. Proper soundproofing would require caulking such gap.


Soundproofing Professionals Use 2 Material Theorems:

  1. Sound Barriers    

    This could include things such as drywall, wood, mass loaded vinyl, steel

  2. Sound Absorbers

    This could include things such as fiberglass insulation, carpet, foamboard

ALERT:   Many materials that you may think are sound barriers may actually be sound absorbers and vice versa.  For example, brick is considered to be a sound absorber.  And many materials have such a composition that they may be considered either or both.

Soundproofing professionals nearly always combine both sound barriers and sound absorbers in any soundproofing design for maximum effectiveness.

Flanking:  Is what happens when you block sound from one direction, it has a way of bouncing off and going around different objects.



This is the number one choice if possible above all of the other common flooring for either or both soundproofing and/or sound conditioning.


If carpet flooring is not possible or not practical in light of other design considerations, then of all the next most common flooring, tile is the next best choice.   You can place rugs or carpet over the tiles in as much area as possible and/or practical for your unique situation and it will usually help your soundproofing and/or sound conditioning efforts.   There is even layout design considerations for sound conditioning with tiles, but this will not do anything for soundproofing.


This is the least desired of the common types of flooring for soundproofing, and usually the worst for sound conditioning.  Though there is underlayment for such type of floors, it does little in the overall grand scheme of the soundproofing design.

Tiles designed for sound conditioning efforts

Sound absorbing noise barrier underlayment
Underlayment for wood or laminate flooring comes in a variety of materials and colors; it helps control sound transmittal when walked upon, but does little overall for soundproofing the room it is installed in.



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