How Do You Soundproof a Booth

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 BoardThicknessNoise reduction (dB) using a sound meter appSTC Noise reduction provided by a barrier materialAbsorption coefficient NRC
2 Drywall ½” layers,
One on each side of the wall
33 dB330.30
2 Drywall ½” layers,
One on each side of the wall PLUS fiberglass insulation inside
39 dB390.65
2 Drywall ⅝” layers,
One on each side of the wall PLUS fiberglass 3.5”  insulation inside
40 dB47+0.70
2 Soundproofing Drywall ⅝” layers
PLUS 4” (or more) mineral wool
60 dB60+1.00
2 Plywood ½” layers,
One on each side of the wall
20 dB200.25

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 ThicknessNoise reduction (dB) using a sound meter appSTC Noise reduction provided by a barrier materialAbsorption coefficient
4 inches50+ dB50 +0.65
2 inches45 dB45 0.50
1 inch30 dB300.25

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.

MaterialAverage STC or dBAbsorption coefficient
Rigid Fiberglass 2” 6.0 PCF380.65
Drywall ½” using two panels (one on each side of a wall) with no other insulation material330.30
Drywall ½” using two panels (one on each side of a wall) PLUS Batts of fiberglass insulation 3.5”390.70

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:

MaterialAverage STC or dBAbsorption coefficient
Blown-in fiberglass insulation360.65
Rigid Fiberglass 2” 6.0 PCF380.65
Drywall ½” using two panels (one on each side of a wall) with no other insulation material330.30

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 sourceNoise dBNoise Reduction Achieved
Street noise in a residential suburb area, through a single 5mm standard window60 dB40 dB
Street noise reduced to 20 dB
Rain noise over the roof and ceiling55 dB40 dB
Rain noise reduced to 15 dB
Frequent dog barking55 dB40 dB
Dog barking noise reduced to 15 dB
Adjacent room60 dB40 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 VinyldB Reduction
½ pound – 0.75 pound10 dB
1 pound14 dB
1.5 pound – 2 pound22 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 paneSTC
A single pane window PLUS a ⅛” acrylic window insert10 – 12 
A single pane window PLUS a ¼” acoustic acrylic window insert18 
A double-pane window PLUS ¼” acoustic acrylic window insert42 – 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 ThicknessSTC
Single pane 26
Double pane28
Single pane PLUS soundproof pane50
Double pane PLUS soundproof pane50 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, mmDensity kg/m3Hollow unit STCSolid unit STC(sand or grout filled)
4” or 102 mm85 – 1,3824044
4” or 102 mm135 – 2,1624548
8” or 203 mm85 – 1,3824452
8” or 203 mm135 – 2,1624957
12” or 303 mm85 – 1,3824857
12” or 303 mm135 – 2,1625363

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 Wall39
4” Structural Clay Tile Wall, PLUS 5/8-in. plaster one face41
6” Brick wall PLUS  3/8-in. gypsum board over 1-in. styrofoam insulation on one face 49
8” Structural Clay Tile Wall45
10” Face Brick Cavity Wall, with 2” air space50
12” Solid Brick Wall59

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 surfaceNRC
360.43cut-acrylic0.50
430.50cut-wool0.55
Carpet on 40 oz/sy Hair Cushion
Pile weight Oz/SyPile height inType of surfaceNRC
320.56cut0.70
Carpet on 40 oz/sy Various Cushion TypesThe more permeable the cushion type the higher the NRC
Cushion WeightCushion MaterialNRC
86Hair0.60
86Hair-jute0.65
41⅜” foam rubber0.60

Acoustic Foam to Soundproof a Booth

The table below shows the absorption coefficients (ASTM C423) of Auralex products:

ProductNRC
1″ Studiofoam Wedges0.50
2″ Studiofoam Wedges0.80
4″ Studiofoam Wedges0.90
MegaMAX-Wall Panels 011.10
2″ Studiofoam Pyramids0.70
4″ Studiofoam Pyramids0.75
Venus Bass Traps1.30

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 paneSTCSTC PLUS acoustic blanket
A single pane window PLUS a ⅛” acrylic window insert10 – 12 25
A single pane window PLUS a ¼” acoustic acrylic window insert18 30
A double-pane window PLUS ¼” acoustic acrylic window insert42 – 45 50

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