Professional audio product recording (audiobooks, audio magazines, podcasts, voice-over narration) requires space without reverberation, echo, and external noises.
To soundproof a room you need several layers of sound barrier materials. To reduce reverb and echo from an adjacent room you need sound absorber materials. These two options can help reduce noise up to 60 dB.
Before you start making a sound booth you need to know how much noise to reduce. Thus you will be able to choose the right sound barrier and sound absorber materials. In this post you will know the STC and NRC ratings of the most reliable soundproof materials:
- Wood boards: Drywall Vs Plywood
- Mineral Wool
- Fiberglass
- Spray Foam
- Gypsum mass
- Mass Loaded Vinyl
- Acrylic Window Inserts
- Glass: Single Pane, Laminated Glass, Double Glazing
- Carpets
- Concrete
- Bricks
- Sound Absorbers: Acoustic Foam
Wood boards: Drywall and Plywood to Soundproof a Booth
Dense materials such as concrete, bricks, and thick wood boards can be good sound barriers.
Wood is less dense than concrete or bricks. Therefore additional materials will be needed to achieve a satisfactory noise reduction level.
The following table will show the STC and NRC ratings of drywall and plywood on boards of different thicknesses: (How Much Noise Can Wood Reduce)
Dry wood is a very poor electricity conductor (10-16σ (S/m) at 20 °C). Thus wood becomes a useful and safe material.
Wood BoardThickness | Noise reduction (dB) using a sound meter app | STC Noise reduction provided by a barrier material | Absorption coefficient NRC |
2 Drywall ½” layers, One on each side of the wall | 33 dB | 33 | 0.30 |
2 Drywall ½” layers, One on each side of the wall PLUS fiberglass insulation inside | 39 dB | 39 | 0.65 |
2 Drywall ⅝” layers, One on each side of the wall PLUS fiberglass 3.5” insulation inside | 40 dB | 47+ | 0.70 |
2 Soundproofing Drywall ⅝” layers PLUS 4” (or more) mineral wool | 60 dB | 60+ | 1.00 |
2 Plywood ½” layers, One on each side of the wall | 20 dB | 20 | 0.25 |
Mineral Wool to Soundproof a Booth
Mineral wool provides excellent results to reduce noise from low to high frequencies. Although it can be more expensive than fiberglass, it can help save some money that would be needed to buy additional materials to reduce the unwanted low-frequency unwanted noise.
Here is a list of how much noise mineral wool can reduce, according to its thickness:
(How much noise can mineral wool reduce)
Mineral Wool Thickness | Noise reduction (dB) using a sound meter app | STC Noise reduction provided by a barrier material | Absorption coefficient |
4 inches | 50+ dB | 50 + | 0.65 |
2 inches | 45 dB | 45 | 0.50 |
1 inch | 30 dB | 30 | 0.25 |
Fiberglass to Soundproof a Booth
After checking the room’s noise with a sound level meter app, as well as a spectrum analyzer app to check exactly what are the most common unwanted frequencies, you can decide if fiberglass is what you need, and what other sound barrier materials can increase the over STC rating.
Drywall or plywood boards play an important role, as they help a bit to reduce noise, in addition to being necessary to build a sound booth.
Material | Average STC or dB | Absorption coefficient |
Rigid Fiberglass 2” 6.0 PCF | 38 | 0.65 |
Drywall ½” using two panels (one on each side of a wall) with no other insulation material | 33 | 0.30 |
Drywall ½” using two panels (one on each side of a wall) PLUS Batts of fiberglass insulation 3.5” | 39 | 0.70 |
Spray Foam to Soundproof a Booth
One type of spray foam is mainly made of isocyanate and polyol resin, mixed and water-blown. The reaction of those components makes spray foam expand 30 – 60 times the volume it gets in its liquid state. Although spray foam provides very good thermal insulation, blown-in fiberglass insulation does a better job:
Material | Average STC or dB | Absorption coefficient |
Blown-in fiberglass insulation | 36 | 0.65 |
Rigid Fiberglass 2” 6.0 PCF | 38 | 0.65 |
Drywall ½” using two panels (one on each side of a wall) with no other insulation material | 33 | 0.30 |
Gypsum Mass to Soundproof a Booth
When using gypsum mass and thick drywall wall, the sound reduction can go from 41 – 45 STC. This result can provide a satisfactory noise reduction level on a tight budget.
Good Soundproofing Example
- 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 |
Mass Loaded Vinyl to Soundproof a Booth
The key to obtaining a good noise reduction level is to use a 1.5-pound MLV sheet. The reduction is effective in all the frequency ranges. Check the best qualities of MLV and how to install it.
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 |
Acrylic Window Inserts to Soundproof a Booth
Acrylic window inserts can help reduce street noise. The best results can be achieved using a ¼” thick acrylic (plexiglass) sheet, window seal rubber, and metal (not plastic) window screen clips. Check more details in this post:
The following chart shows the STC of a window insert:
Type of pane | STC |
A single pane window PLUS a ⅛” acrylic window insert | 10 – 12 |
A single pane window PLUS a ¼” acoustic acrylic window insert | 18 |
A double-pane window PLUS ¼” acoustic acrylic window insert | 42 – 45 |
Glass: Single Pane, Laminated Glass, Double Glazing to Soundproof a Booth
A single standard glass pane 5 mm thick (7/32”) is STC 20 on average. Satisfactory results STC 35+ can be achieved by having 2 double glazing panes 9 mm thick and 7 mm thick with an 11 mm gap in between. The thicker the glass pane the more reduction can be obtained.
Here there is a list of the STC obtained with different combinations of glass panes:
Glass Thickness | STC |
Single pane | 26 |
Double pane | 28 |
Single pane PLUS soundproof pane | 50 |
Double pane PLUS soundproof pane | 50 Using double pane is not worth it |
I have seen many sound booths’ walls with double glazing and argon gas to reduce external noise. In that case, just make sure to cover the inner walls with acoustic foam to achieve from 40% to 60% absorption. Brands such as Auralex reach up to 80%.
Concrete and Bricks to Soundproof a Booth
Concrete is a very dense sound barrier material, with little sound absorption rate. The thicker the concrete wall the more noise reduction can be achieved. Bricks have a very similar response in matters of noise reduction:
Concrete Thickness in, mm | Density kg/m3 | Hollow unit STC | Solid unit STC(sand or grout filled) |
4” or 102 mm | 85 – 1,382 | 40 | 44 |
4” or 102 mm | 135 – 2,162 | 45 | 48 |
8” or 203 mm | 85 – 1,382 | 44 | 52 |
8” or 203 mm | 135 – 2,162 | 49 | 57 |
12” or 303 mm | 85 – 1,382 | 48 | 57 |
12” or 303 mm | 135 – 2,162 | 53 | 63 |
A hollow 4” brick has an average of 39 STC. Take a look at the following STC rating on 4” to 12” bricks:
Thickness | STC |
4” Structural Clay Tile Wall | 39 |
4” Structural Clay Tile Wall, PLUS 5/8-in. plaster one face | 41 |
6” Brick wall PLUS 3/8-in. gypsum board over 1-in. styrofoam insulation on one face | 49 |
8” Structural Clay Tile Wall | 45 |
10” Face Brick Cavity Wall, with 2” air space | 50 |
12” Solid Brick Wall | 59 |
Sound Absorber Materials to Soundproof a Booth
Applying sound absorber materials on an adjacent (noisy) room’s inner wall can absorb reverb and help reduce noise in the area where a sound booth wants to be placed. The most common sound absorber materials are carpets, acoustic foam, and acoustic blankets.
Check many more details here. Let’s take a look at their Noise Reduction Coefficients:
Carpets to Soundproof a Booth
Carpet on Concrete, with no Cushion | |||
Pile weight Oz/Sy (Fiber weight only, backing not included) | Pile height in (Fiber height, backing not included) | Type of surface | NRC |
36 | 0.43 | cut-acrylic | 0.50 |
43 | 0.50 | cut-wool | 0.55 |
Carpet on 40 oz/sy Hair Cushion | |||
Pile weight Oz/Sy | Pile height in | Type of surface | NRC |
32 | 0.56 | cut | 0.70 |
Carpet on 40 oz/sy Various Cushion TypesThe more permeable the cushion type the higher the NRC | ||
Cushion Weight | Cushion Material | NRC |
86 | Hair | 0.60 |
86 | Hair-jute | 0.65 |
41 | ⅜” foam rubber | 0.60 |
Acoustic Foam to Soundproof a Booth
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 |
Acoustic Blankets to Soundproof a Booth
Acoustic blankets are a very common material for portable sound booths mounted on a PVC
frame. They do a very good absorption job with an average of 40% NRC. The following table shows how much noise does a window insert and acoustic blanket reduce
Type of pane | STC | STC PLUS acoustic blanket |
A single pane window PLUS a ⅛” acrylic window insert | 10 – 12 | 25 |
A single pane window PLUS a ¼” acoustic acrylic window insert | 18 | 30 |
A double-pane window PLUS ¼” acoustic acrylic window insert | 42 – 45 | 50 |