A plain-English glossary of the soundproofing terms you’ll see on our service pages, in cost guides, and in UK Building Regulations. If something here isn’t clear, ask us — we’d rather explain it than sell you the wrong system.
Airborne noise vs impact noise
Airborne noise is sound that travels through the air — speech, TV, music. It passes through walls, floors and ceilings by making them vibrate. Impact noise is sound caused by something physically hitting a surface — footsteps, dropped objects, furniture dragging. It needs a different fix (decoupling, mass, damping) than airborne noise alone.
STC (Sound Transmission Class)
A single-number rating used mainly in the US to describe how well a partition blocks airborne noise. Higher is better. A standard studwork wall is ~STC 33; a decent residential separating wall is ~STC 50. In the UK we more commonly quote Rw or DnTw instead of STC — they measure broadly the same thing but with different test conditions.
Rw (Weighted Sound Reduction Index)
UK/European lab measurement of a building element’s airborne sound insulation, expressed in dB. A dense-block wall might score Rw 53 dB in the lab. Real-world performance is always lower than the lab Rw because of flanking paths and workmanship — which is why UK Building Regs use DnTw, a field measurement.
DnTw (Standardised Level Difference)
On-site field measurement of airborne sound insulation between two rooms, in dB. UK Building Regulations Part E requires a minimum of DnTw 43 dB for separating walls and 45 dB for separating floors in new build conversions (England & Wales). This is the number that matters when you’re doing a flat conversion that has to pass acoustic testing.
L’nT,w (Impact Sound Pressure Level)
Field measurement of impact noise transmission through a floor — specifically how much sound a standard tapping machine produces in the room below. Lower is better. Part E requires L’nT,w ≤ 62 dB for separating floors in conversions.
Flanking noise
Sound that bypasses the wall, floor or ceiling you’ve soundproofed by travelling through an adjacent path — a shared joist, a continuous plasterboard, a service penetration, a weak window reveal. Flanking is why a soundproofed wall can still sound disappointing: the sound went around it, not through it. Every proper soundproofing design addresses flanking paths. See our page on flanking noise.
Decoupling
Physically separating two surfaces so vibration can’t pass directly between them. Examples: resilient bars that break the rigid connection between plasterboard and stud; floating floors that sit on acoustic layers; independent walls built off their own studwork, not touching the original structure. Decoupling is one of the four pillars of soundproofing (the others being mass, absorption and damping).
Mass
The “M” in “mass-spring-mass” soundproofing. Heavier materials transmit less sound. Mass is why double plasterboard beats single, and why acoustic plasterboard (denser) beats standard. There’s a ceiling to what mass alone can do — at some point you have to decouple and damp as well.
MLV (Mass Loaded Vinyl)
A dense, flexible vinyl sheet used to add mass to walls, floors and ceilings without building up thickness. Useful in retrofit projects where structural depth is at a premium. On its own it’s not a complete system — it needs to pair with decoupling and absorption to be worth the cost.
Green Glue
A damping compound applied between two layers of plasterboard (or other rigid panels). It converts vibration energy into tiny amounts of heat, reducing transmission — especially at low frequencies where mass alone struggles. Often used in double-layer ceilings and walls.
Resilient bar / resilient channel
A thin metal channel fixed to studs or joists; the plasterboard then screws to the channel, not to the structure. This decouples the plasterboard from the frame and cuts vibration transmission significantly. Easy to get wrong — resilient bars must not be bridged (no screws that pass all the way through into the stud), or the decoupling is lost.
Independent wall
A new stud wall built just in front of the existing wall, not touching it. Fully decouples the old structure from the new finish. Highest-performing wall system — we typically see ~26 dB improvement on top of the original wall — but takes the most floor depth (100–180 mm).
Acoustic absorption (vs soundproofing)
Absorption reduces sound inside a room — soaking up reflections so the room sounds calmer and speech becomes clearer. Soundproofing stops sound entering or leaving a room. They’re different problems needing different materials: porous foam and mineral-wool panels for absorption; mass, decoupling and damping for soundproofing. A studio or home cinema usually needs both.
NRC (Noise Reduction Coefficient)
A single-number rating of how absorptive a material is, on a 0–1 scale. NRC 0.85 means a material absorbs ~85% of sound that hits it (averaged across speech frequencies). Relevant for acoustic treatment (absorption panels, ceiling clouds), not for soundproofing walls.
UK Building Regulations Part E
The section of the Building Regulations (England & Wales) covering resistance to the passage of sound in and between dwellings and rooms for residential purposes. Requires testing on completion for new-build and material conversions. Minimums: DnTw 43 dB airborne (walls), 45 dB airborne and L’nT,w ≤ 62 dB impact (floors). Higher numbers required for some room types. See Approved Document E.
BS 8233
UK standard giving guidance on sound insulation and noise reduction for buildings. Commonly cited figure: indoor ambient noise levels of 35 dB LAeq in bedrooms during the day and 30 dB at night for a good acoustic environment. Not a legal minimum, but a useful benchmark for what “acceptable” sounds like.
Still not sure?
If you’ve read this and still can’t tell whether you need mass, decoupling, absorption, or all three — that’s exactly what a site survey is for. Book a free survey and we’ll measure the room, identify the dominant path (airborne, impact, flanking), and send you a written recommendation with real numbers, not a sales script.
Acoustic plasterboard (e.g. SoundBloc)
A denser plasterboard designed to improve airborne sound insulation of walls and ceilings. British Gypsum SoundBloc is the dominant UK product — a 15 mm board with a single-layer Rw of ~36 dB. Two layers of SoundBloc on a resilient-bar system can bring a party wall to DnTw ~45 dB, meeting Part E for new-build separating walls. Standard plasterboard gives no measurable benefit by comparison.
Noise nuisance (UK law)
Under the Environmental Protection Act 1990, section 79, noise from premises that is “prejudicial to health or a nuisance” is a statutory nuisance. Local authorities have a duty to investigate complaints. If they agree it’s a nuisance, they can serve an abatement notice — breach is a criminal offence carrying fines up to £5,000 for a household or £20,000 for business premises. Statutory nuisance is separate from (and usually slower than) private civil action. Councils typically ask complainants to keep a noise diary for 2–4 weeks before acting.
London Plan Policy D14 (Agent of Change)
Policy D14 of the London Plan puts the acoustic burden on the new development — a flat built next to an existing venue must soundproof itself; the venue is not required to quieten down. Since March 2018 this principle has materially affected planning outcomes for developers and change-of-use applications in London.