Overview
When evaluating acoustic materials like MDF slatted panels or PET felt, the most common metric you will encounter is the NRC, or Noise Reduction Coefficient. For contractors and distributors, understanding NRC is essential for recommending the right products to clients.
Defining NRC
The Noise Reduction Coefficient is a single-number rating that represents how much sound an acoustic product absorbs. It is an average of the material's sound absorption coefficients at four specific mid-range frequencies: 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz. These frequencies roughly cover the range of human speech.
How to Read an NRC Rating
NRC ratings typically range from 0.0 to 1.0. An NRC of 0.0 indicates a perfectly reflective material that absorbs no sound (e.g., thick concrete or glass). An NRC of 1.0 indicates a perfectly absorptive material that absorbs 100% of the sound (e.g., an open window). An acoustic panel with an NRC of 0.80 absorbs 80% of the sound that hits it and reflects 20% back into the space.
What Is a Good NRC Rating?
The required NRC depends on the application.
- NRC 0.40 - 0.60: Good for general noise reduction in moderately noisy environments such as restaurants and general office spaces.
- NRC 0.70 - 0.90+: Excellent absorption, required for environments where speech intelligibility is critical, such as recording studios, conference rooms, and auditoriums.
How to Improve NRC Through Installation
The NRC of an MDF slatted acoustic panel is not fixed — it can be significantly improved by the installation method. Installing panels on timber battens with a 50mm air gap behind them, filled with mineral wool or acoustic insulation, can boost the system's NRC from 0.50 to 0.85 or higher. The air cavity allows sound waves to be trapped and absorbed more effectively, particularly at lower frequencies.