Systems available in India and what they achieve
| System | Typical NRC | Rate (₹/sq ft installed) | Look | Best for |
|---|---|---|---|---|
| 9 mm PET felt panel, direct fixed | 0.35 – 0.50 | ₹120 – 200 | Flat felt, many colours | Budget offices, phone booths |
| 12 mm PET felt with 25 mm air gap | 0.55 – 0.70 | ₹170 – 260 | Same, on a batten frame | Meeting rooms; the air gap does the work |
| Grooved MDF with acoustic backing | 0.55 – 0.75 | ₹280 – 450 | Timber-look slats or perforations | Boardrooms, home theatres, reception walls |
| Fabric-wrapped glasswool, 50 mm | 0.85 – 0.95 | ₹320 – 520 | Flush fabric panels | Recording spaces, serious home theatres |
| Perforated gypsum ceiling board | 0.55 – 0.70 | ₹180 – 320 | Continuous ceiling, small perforations | Open offices, large meeting rooms |
| Baffles and hanging rafts | 0.80 – 1.00 per sqm of baffle | ₹450 – 650 | Suspended vertical fins | Open-plan floors with exposed services |
Absorption is not insulation
This distinction decides whether a project succeeds. Absorption reduces reflected sound within a room — echo, reverberation, the hard ring of a bare boardroom. Insulation reduces sound transmitted between spaces — the colleague you can hear through the wall.
- If the complaint is “the room echoes” or “calls are unintelligible”, absorption panels are the correct answer.
- If the complaint is “we can hear the meeting from outside”, panels will not help. That needs mass and sealing: a double-stud partition, glasswool in the cavity, two layers of board each side, full-height construction to the slab, and acoustic seals on the door.
- The commonest failure in a Mumbai office fit-out is a beautiful panelled meeting room whose partition stops at the false ceiling. Sound travels over the top through the ceiling void, and no panel on any wall will change that.
- Doors and glazing are usually the weakest element. A 35 dB partition with an unsealed hollow-core door performs at about 22 dB.
Coverage maths for a real room
For a 16 × 12 ft meeting room with a 9 ft 6 in ceiling, the total surface area of walls and ceiling is roughly 725 sq ft. At 25% coverage that is about 180 sq ft of panel.
- Start with the ceiling. It is the largest uninterrupted surface and usually the cheapest to treat. A perforated gypsum ceiling or 60 sq ft of baffles does a great deal.
- Treat the wall behind the display screen and the wall opposite it. Those are the first reflection points for a person speaking at the head of the table.
- Leave the side walls partly hard. A completely absorbent room sounds dead, and people instinctively raise their voices in it.
- Add soft furnishings to the count. Carpet, upholstered chairs and curtains are absorption, and a carpeted room needs less panelling than a tiled one.
- At 180 sq ft of NRC 0.7 panelling, budget ₹35,000–80,000 for that room depending on the system chosen.
Fire, cleaning and Mumbai commercial realities
- Commercial landlords in BKC, Lower Parel and Andheri routinely specify fire performance for wall linings in their fit-out manuals. PET felt is available in flame-retardant grades; check before ordering, because replacing an installed lining is expensive.
- Fabric-wrapped glasswool panels must be sealed at the edges. Loose mineral fibre in an air-conditioned office is a legitimate complaint.
- Humidity does not affect PET felt or glasswool behind fabric, but it does affect grooved MDF. Use moisture-resistant board in any panel near an external wall or an AC outlet where condensation forms.
- Cleaning: PET felt is vacuumed with a brush head. Fabric-wrapped panels stain and cannot be washed; keep them above chair-back height in a meeting room.
- Panels at desk level get damaged. In an open office, treat the ceiling and the upper wall and leave the lower 900 mm hard.
Care, life and BOQ wording
- Vacuum panels twice a year. Replace individual panels rather than re-lining a wall — specify a fixing system that allows it.
- Expected life: 12–15 years for PET felt, longer for grooved timber, shorter for fabric in a high-traffic area.
- BOQ: “Acoustic wall lining in 12 mm PET felt panel, flame-retardant grade, NRC not less than 0.60 when installed on 25 mm battens with air gap; fixing system to permit individual panel removal.”
- BOQ: “Contractor to submit the manufacturer’s test certificate for NRC and fire classification before installation.”
- BOQ: “Acoustic partitions to be built full height to the structural slab with cavity insulation and perimeter acoustic sealant; doors to have drop seals and perimeter gaskets.”
Specification summary
| Property | Specification |
|---|---|
| Target NRC | 0.60 minimum installed; 0.85 for critical rooms |
| Coverage | 20 – 30% of total wall and ceiling area |
| Air gap | 25 mm behind felt panels — it raises NRC substantially |
| Fire | Flame-retardant grade; check landlord fit-out manual |
| Rate | ₹120 – 650 per sq ft installed, ex-GST |
| Priority surfaces | Ceiling, then the two walls facing the speaker |
| Not a substitute for | Full-height partitions, sealed doors, cavity insulation |
| Life | 12 – 15 years |
Frequently asked questions
Will acoustic panels stop noise coming from the next room?+
No. Panels absorb sound inside the room they are in. Stopping transmission needs mass and airtightness — a full-height partition with cavity insulation, two board layers each side and a properly sealed door. Panels on the wall do almost nothing for that problem.
What NRC should I ask for?+
0.60 or better as installed for a meeting room, 0.85 and above for a recording space or a serious home theatre. Anything under 0.40 is a decorative finish with a small acoustic benefit. Ask for the test certificate, and note that the installed value with an air gap differs from the bare panel value.
How much of a room needs to be covered?+
Twenty to thirty per cent of the combined wall and ceiling area is the usual target for speech clarity. Beyond about fifty per cent the room becomes uncomfortably dead and people speak louder to compensate. Position matters more than raw quantity.
Are acoustic panels worth it in an open-plan office?+
Yes, and the ceiling is where to spend. An absorbent ceiling or hanging baffles across an open floor plate reduces the general noise level more than any wall treatment, because most reflections in an open office come off the ceiling.
Do acoustic panels work in a home theatre?+
They are essential, but they are half the job. A home theatre also needs the room sealed and the low frequencies controlled with bass traps in the corners. Fabric-wrapped 50 mm panels at the first reflection points plus corner traps is the standard starting specification.