What Is A Noise Reduction Coefficient (NRC) Rating?

Noise Reduction Coefficient (also known as ANC) is a rating system that goes from 0 to 1.0, the score tells you how effective an acoustic item is at absorbing sound.

The NRC Rating Scale

A score of 0 means the item absorbs no sound.

A score of 0.5 means the item absorbs 50% of sound and reflects the other 50%.

A score of 1 means the item absorbs 100% of sound and no sound is reflected back.

A high score 0.9+ is ideal for use in rooms such as recording studios where minimising echo is essential.

How Is NRC Calculated?

Working out the exact NRC rating of an acoustic item requires the following things; a sound test room, a finely tuned microphone and a sound frequency measurement device.

Needless to say, most of us won't be able to get hold of the necessary equipment to carry out these kinds of tests, however acoustic equipment specialists will do and should include the NRC rating in their product descriptions.

wave sound file

An NRC test typically looks something like this:

  1. A noise is played in the sound lab, and noise levels are recorded. This tells the equipment what an NRC score of 0 would sound like.
  2. The item (such as an acoustic board) is placed in the room and noise is played at a number of different frequencies.
  3. Measurements are counted up and an average score is determined
  4. The product is assigned it's NRC score.

Products That Use NRC Ratings

NRC ratings are widely used in the soundproofing industry, although don't let that fool you into thinking a product with an NRC score of 1 will be great for soundproofing.

NRC ratings are used for sound dampening, so while they do a great job of preventing echo within a room they will not necessarily do much to block sound from leaving the room and disturbing people outside.

A few products that you can often find NRC ratings on include:

NRC rated ceiling tiles

What are NRC Products Useful For?

Products with high NRC Ratings are great for dampening sound and reducing echo.

As such they are invaluable in places where sound quality is important, or in noisy environments where a bad echo can double the noise.

Noise Reduction products are commonly used in recording studios, cinemas, home cinemas and live performance venues.

NRC products are very effective in places where there are large rooms with hard flooring as these create a lot of echo. Places such as churches, schools, universities and sports centres can all benefit from using these type of products.

When a room gets busy it gets noisy (thing songs at church, a busy canteen or restaurant etc), the noise bounces off hard surfaces and back into your ears making the room sound even louder than it is.

Using sound dampening products with a high NRC rating to reduce echo can make a noisy room significantly quieter.


We hope this article has helped you to understand a bit more about NRC Ratings, what they are and how you can use them to get the best sound dampening products.

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Welcome to Soundproof Panda!

My name is Dan and I live very close to an internationally famous stadium which generates an awful lot of noise that I'd rather block out!

This site is my place to share what I've been learning on my soundproofing journey.
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