What Is NRC? A Plain-English Guide to Choosing Acoustic Panels

When you compare acoustic panels you will see a number called NRC, the Noise Reduction Coefficient. It is the single most useful figure for comparing absorbers, but it is often misunderstood.

What NRC means

NRC is a number between 0 and about 1 that describes how much sound a material absorbs, averaged across the main speech frequencies (250, 500, 1000 and 2000 Hz). An NRC of 0 means the surface reflects everything, like glass or polished stone. An NRC of 1.0 means it absorbs essentially all of the sound that hits it at those frequencies.

Typical NRC values

• Marble, glass, concrete: around 0.0–0.05
• Painted gypsum board: around 0.05–0.10
• Heavy curtains: around 0.40–0.60
• 9 mm PET panel: 0.45–0.60
• 12 mm PET panel: 0.45–0.75
• 24 mm PET panel: up to 1.0

Why thickness matters

Low-frequency sound has longer wavelengths, and thin absorbers cannot capture much of it. Thicker panels, or panels mounted with an air gap behind them, extend absorption downward. That is why 24 mm panels outperform 9 mm panels, and why bass traps exist for studios and cinemas.

NRC is not soundproofing

A high NRC means less echo inside the room. It does not mean the panel blocks sound from passing through a wall. Blocking needs mass and sealing, measured by STC or Rw ratings. If your problem is a neighbour's TV, you need an MLV barrier or a better wall, not just high-NRC panels.

How to choose

• Decorative walls, corridors, retail: 9 mm
• Offices, bedrooms, classrooms, living rooms: 12 mm
• Meeting rooms, restaurants, studios, mosques: 24 mm

Coverage matters as much as NRC. Ten square metres of a 0.75 panel does more than three square metres of a 1.0 panel. Send us your room sizes and we will calculate both.