Acoustic foam is a very poor noise reduction material, but excellent reverb and echo absorber inside a sound booth or recording room of a sound studio.
If you want to block sound, acoustic foam is not what you should use but mineral wool or fiberglass. The STC rating of acoustic foam is under 0.05.
These are the qualities of acoustic foam inside a sound booth to record audiobooks, podcasts, and many other types of voice-over audio products.
- Noise Reduction Coefficient: Acoustic foam is dense and thick and it’s easy to recognize because of its peculiar pyramid pointed or wedged surface.
These shapes help interfere with the sound waves inside the sound booth thus absorbing reflections, reverb, and any possible echo during the recording stage.
The table below shows the absorption coefficients (ASTM C423) of Auralex products:
| Product | NRC |
| 1″ Studiofoam Wedges | 0.50 |
| 2″ Studiofoam Wedges | 0.80 |
| 4″ Studiofoam Wedges | 0.90 |
| MegaMAX-Wall Panels 01 | 1.10 |
| 2″ Studiofoam Pyramids | 0.70 |
| 4″ Studiofoam Pyramids | 0.75 |
| Venus Bass Traps | 1.30 |
- How Much Reverb and Echo Can Acoustic Foam Absorb: the NRC (noise reduction coefficient) is 0.50 – 1.75 on average on professional acoustic foam products. In a sound booth for recording audiobooks and podcasts, make sure all the surfaces of the inner walls are covered with acoustic foam panels.
- Safety: As foam is mainly made of synthetic rubber, natural latex or polyurethane, or extruded melamine, acoustic foam brands offer a fire-retardant component in their products.
- Weight and installation: Acoustic foams are very light and easy material to install. To make sure they won’t fall off, you can use stick tabs, liquid spray adhesive or liquid adhesive. In the following video, you can see the way to apply liquid adhesive correctly: https://www.youtube.com/watch?v=coiQMPmgi9s&t=104s
How Much Noise Can Spray Foam Reduce (STC 36)
Although spray foam is a very popular reliable insulation material, the noise reduction achieved by applying about 6” gets only an STC of 36 on average. To get better results, consider using at least 2 layers of Type X or Soundproof Drywall ⅝” thick.
How Much Noise Can Mass Loaded Vinyl (MLV) Reduce
In addition to being a very flexible material, mass-loaded vinyl is specifically used as a sound barrier for noise reduction purposes. The best results can be obtained using a 1.5-pound layer of mass-loaded vinyl.
Mass-loaded vinyl is mainly composed of high-mass barium sulfate, calcium carbonate as a soundproofing material, and vinyl for flexibility.
| Amount of Mass Loaded Vinyl | dB Reduction |
| ½ pound – 0.75 pound | 10 dB |
| 1 pound | 14 dB |
| 1.5 pound – 2 pound | 22 dB |
Best Qualities of Mass Loaded Vinyl (STC 25 – 27)
- MLV can also help absorb sound and can be used to wrap and fold as needed.
- This feature is ideal when you use a silent air vent ventilation system, as you can wrap the flexible conduit and insulate the inner sides of the box where it is placed.
- This double benefit (sound barrier and sound absorber) is something that no other absorbing material has (mineral wool, fiberglass, wallboards).
- Although MLV is not 100% fire-resistant, it would need to be exposed to high temperatures (80°C+) for extended periods of time to ignite. Thus MLV is safer than acoustic foam.
- Latex paint can be applied on MLV in case the black and grey original colors in it don’t comply with the aesthetics of the sound recording area (studio, vocal booth).
How to Install Mass Loaded Vinyl on Walls
- Start with a top corner of the wall you want to soundproof. Ask someone to help you.
- Make sure it is straight and staple it every 5 cm.
- Tape the adjacent edges with duct or foil tape,
- Use acoustical sealant on all the perimeter of the wall.
- Apply the other insulating materials if needed (drywall, mineral wool, fiberglass).
How to Seal Sound Leakage in a Sound Booth or Wall
When making a soundproof wall it’s necessary to make sure that all possible sound leakage is fixed before the wall is finished.
When the wood board edges get close tight, there still can be a little leakage. It’s very common to cover the adjacent edges with extra gypsum. Make sure you also use edge tape and finally apply high-quality acrylic latex caulk (acoustical sealant).
How Much Noise Can Extruded Polystyrene Reduce
Extruded polystyrene is a thermostatic polymer, with a very good impermeability level. Although it’s used as a thermal insulation material, its soundproofing capabilities are lower than MLV and spray foam.
As extruded polystyrene is not popular for its soundproofing but thermal insulation qualities, it has not officially been STC ranked. Nevertheless, I tested a single 1” thick layer and it provides a 10 – 12 dB noise reduction.
If it’s used with other sound barrier materials such as 2 ½” layers of Type X drywall it can get an average of 33 dB reduction.
Combinations to Make An Efficient Soundproof Wall
Taking a look at the following study case, the noise reduction obtained goes from 40 dB to 60 dB.
Good Soundproofing
- 2 5/8” layers Type X drywall
- 3 layers of gypsum mass (total ½”)
- STC 41 – 45
| Sound source | Noise dB | Noise Reduction Achieved |
| Street noise in a residential suburb area, through a single 5mm standard window | 60 dB | 40 dB Street noise reduced to 20 dB |
| Rain noise over the roof and ceiling | 55 dB | 40 dB Rain noise reduced to 15 dB |
| Frequent dog barking | 55 dB | 40 dB Dog barking noise reduced to 15 dB |
| Adjacent room | 60 dB | 40 dB Adjacent room noise reduced to 20 dB |
Very Good Soundproofing
- 2 5/8” layers Type X drywall
- 3 layers of gypsum mass (total ½”)
- 1 layer 2.5” fiberglass
- STC 46 – 50
| Sound source | Noise dB | Noise Reduction Achieved |
| Street noise in a residential suburb area, through a single 5mm standard window | 60 dB | 45 dB Street noise reduced to 20 dB |
| Rain noise over the roof and ceiling | 55 dB | 45 dB Rain noise reduced to 15 dB |
| Frequent dog barking | 55 dB | 45 dB Dog barking noise reduced to 15 dB |
| Adjacent room | 60 dB | 45 dB Adjacent room noise reduced to 20 dB |
Excellent Soundproofing
- 3 5/8” layers of Soundproof drywall
- 3 layers of gypsum mass (total ½”)
- 1 layer 2.5” fiberglass
- 1 layer 1.5 MLV
- STC 60+
| Sound source | Noise dB | Noise Reduction Achieved |
| Street noise in a residential suburb area, through a single 5mm standard window | 60 dB | 50 dBStreet noise reduced to 20 dB |
| Rain noise over the roof and ceiling | 55 dB | 50 dB Rain noise reduced to 15 dB |
| Frequent dog barking | 55 dB | 50 dB Dog barking noise reduced to 15 dB |
| Adjacent room | 60 dB | 40 dBAdjacent room noise reduced to 20 dB |