NRC Ratings: What Is a Noise Reduction Coefficient?

A Noise Reduction Coefficient is an average rating of how much sound an acoustic product can absorb. (How much quieter a product can make your space.) Like a sponge absorbs water, an acoustic product absorbs sound and the NRC tells us just how much sound those products can soak up.

The Scale

NRC ratings range from 0 to 1. An NRC of 0 means that the product absorbs no sound. An NRC of 1 means that the product absorbs all sound. The higher the NRC, the better the product is at soaking up sound

The thickness and density of a product are two factors in calculating a Noise Reduction Coefficient. An acoustic product with a .95 NRC rating means that 95% of sound in the space is absorbed, while the other 5% is reflected.



At 0 NRC, there is no sound absorption. The sound bounces off of a smooth surface and back into the room, as shown by the red waves.

NRC 0.5


At 0.5 NRC, only 50% of the sound is being absorbed by the acoustic product, while the other 50% is being reflected back into the room.



At 1 NRC, 100% of the sound is being absorbed by the acoustic product, and no sound is being reflected back into the room.


Calculating the NRC for an acoustic product is no small task. There are a few different ways to determine NRCs, the following is an explanation of how our products are tested for NRC using the ASTM Standard Test Method for Sound Absorption.

A special sound test lab room specifically designed for measuring sound absorption is equipped with a  microphone and fancy equipment that measure sound frequencies.

  • To begin the test, an initial measurement is taken by transmitting a noise signal into the room and the equipment takes a  measurement of how much sound was absorbed.
  • Once the initial measurement is taken, the product being tested is placed in the same test lab, and the sound absorption is measured at four different frequencies.
  • The NRC is calculated by averaging the various measurements and rounded off to the nearest 0.05.

How our products stack up

It’s important to note that the effectiveness of acoustic products depends largely on the size of the space and how the product is installed. All of our products receive high NRC ratings, making them the perfect choice for bringing peace to your space.

Ready to hear the difference? Reach out to one of our highly knowledgeable Acoustic Specialists or fill out a free room analysis form to find the best acoustic solution for you!