Acoustics 101: Understanding NRC Ratings

What is an NRC Rating? The Noise Reduction Coefficient rating and how it applies to acoustical materials, reduced sound reverberation and sound clarity within a space. The Key to Choosing Sound-Absorbing Materials.

According to a study by the WHO, noise pollution is now recognized as a serious threat to public health. The good news is that there are ways to combat noise pollution, and one of the most effective methods is through sound-absorbing materials. How does this sound absorption work? Materials that absorb sound are largely converting sound energy into heat energy.

When designing room acoustics, there are many different ratings that may be applied to a product to identify how it will shape the sound of a space or between spaces. You may come across ratings for NRC (Noise Reduction Coefficient), SAA (Sound Absorption Average), STC (Sound Transmission Class), IIC (Impact Insulation Class) or CAC (Ceiling Attenuation Class).

The Noise Reduction Coefficient (NRC) Rating of a product is a simplified measurement of how well a material absorbs sound. The rating is an average given on a scale from 0 to 1, with 0 being perfectly reflective and 1 being completely absorptive. The average is calculated using the sound absorption coefficients at 4 frequencies of 250, 500, 1000, 2000 Hertz. NRC Ratings are rounded to the nearest 0.05. BASWA Systems have NRC Ratings from 0.80 to 1.00.

But why is this important? Choosing materials with high NRC ratings can greatly reduce noise levels in a space, creating a quieter and more comfortable environment. This can be particularly important in areas where sound privacy is essential, such as offices or healthcare facilities.

When it comes to selecting sound-absorbing materials, acoustical plaster is a top choice due to its high NRC rating and aesthetic appeal. It can easily be applied to walls or ceilings and comes in a variety of finishes and colors.

To understand how a material would perform in an actual installed environment, seek a product’s third party test data for the ASTM-C423 standard for broad range sound absorption coefficients, SAA and NRC Ratings. BASWA Systems have been tested using ASTM-C423 A & E Mounting in order to give the most accurate indication of its performance characteristics in multiple installation conditions. Uniquely, BASWA systems are acoustically consistent in performance, despite differing installation conditions from project to project, due to its simplistic system installation requirements.

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