As means to deaden sounds and keep a space as soundproof as possible,
a material like Spray foam could be a consideration.
Spray foam acts as insulation for walls and ceilings and maybe effective when paired with other materials that have mass.
Spray foam on its own is not an effective soundproof material, but it may be a great option for insulation and one that is cost effective,
Types of Spray foam
Closed Cell Spray Foam
This type of spray foam has the ability to expand between 30 to 50 times its original size when it hardens.
It is usually used with a hydro-fluorocarbon to deliver the mixture to the surface I.e. wall or ceiling.
When hardened the polyurethane is impermeable to any moisture or vapor.
Hardened spray foam has a strength of around 28 psi, which makes it ideal and a great way to shield against anything as destructive as an earthquake.
Open Cell Spray Foam
As far as expansion goes, open cell spray foam will expand to about 150 times its original volume.
With open cell spray foam water is used as a secondary material to drive the blended material into the wall or cavity into which it expands.
Compared to closed cell spray foam, open cell spray foam is only slightly more flexible.
It is a great way to trap airflow therefore making it a great thermal barrier.
Open cell spray only has a strength of about 4.0 psi.
Noises that Spray Foam attempts to Control
With spray foam , the two types of noises that you may try to get rid of are Airborne and impact noises.
basically, sound waves are vibrations at their core and they are called airborne because they basically travel through the area until they run into something.
When they run into an obstacle they vibrate their way through the object and continue on.
Not all sound waves will be absorbed or reflected therefore less waves travel onward, which in turn reduces the intensity of the sound.
Barriers only work to a certain extent and hence will not absorb all frequencies, some will not be absorbed.
Take the example of drums that take time to decrease from the time their hit, they usually have a reverberation effect that is harder to dampen.
Mid range and high range frequencies are much easier to mute or reduce.
Impact noises are the second type of noises that spray foam tries to get rid of or atleast dampen.
These are typically noises that occur when something hits the surface either inside or outside a structure.
Impact noises will usually be called structural sounds and they are able to echo throughout a building.
Spray foam as a way to reduce noise
Spray foam has great thermal properties but when we gather what has been discussed on open and closed cell spray we can easily deduce that polyurethane may not be good as a soundproofing material.
It simply doesn’t have the mass to absorb sound.
Furthermore, when spray foam hardens, it becomes rigid which makes it bad material for sound absorption.
You can easily notice the amount of resonance that would be present in the space that has been utilized with spray foam.
For proper sound absorption you need a material that is softer and not rigid.
Also take note that while spray foam could be used as insulation with other soundproof material,
using it with decoupling is a bad idea.
Sprayfoam maybe great for securing against earthquakes and hurricanes but bad for decoupling.
Alternatives for soundproofing
Now that we’ve established that spray foam not good as a sound proof material, lets look into some alternatives.
Retrofit is a great way to insulate and improve the sound proofing properties of existing walls.
cellulose insulation is an impeccable sound absorption material that can reduce reverberation and feedback.
This may seem like a time consuming undertaking but trust that a fresh and new start will do you some good.
By basically reconstructing a space you can choose the materials to employ and choose the materials to disregard.
It maybe helpful to hire a soundproof expert to assess your space and make recommendations of the materials that would be required.
From this posts observation and various research on this topic.
Spray foam is an ideal thermal insulation tool but a bad sound proof material.