What is NRC Rating? Noise Reduction Coefficient Explained


When people are looking to reduce the noise inside of a certain area, one of the best ways to measure certain setups is to go off of the Noise Reduction Coefficient rating. Known as the NRC for short, many people and companies have relied on this for years as one of the quickest ways to gather information. It is not necessarily the only information a person needs before starting, but it does provide plenty of beneficial information to narrow down the search.

While many people have seen an NRC Rating listed before, knowing how someone arrives at that number is something entirely different. Here’s how the NRC Rating works, and how dependable it is for shoppers.

Breaking Down NRC Ratings

NRC ratings have a range of 0 to 1. It might seem like a pretty simple scale, but some companies become very specific with the percentages they offer, down to the nearest 0.05. If a product absorbs no sound at all, it has an NRC of 0. If it absorbs all sound and no sound is reflecting into the room, it has an NRC of 1.

Anything between 0 and 1 is essentially a percentage of the amount of sound that is absorbed by an acoustic product. If 60% of the sound is absorbed, the product will have a 0.60 NRC. When people are making purchases and specifically looking to reduce sound bouncing around, a high NRC is what people are searching for.

What Dictates a Product’s NRC Rating?

The two biggest factors with any type of product when it comes to their NRC rating is thickness and density. If a product can efficiently absorb sound, it is going to be pretty thick and dense overall usually.

Every material in the world has some type of impact on acoustics. They can be tested to show how a certain set up might be, but most of the time, an NRC Rating will only come with products specifically designed for acoustics. For example, a shoebox could have a small impact on sound absorption, but it’s not going to include an NRC Rating because it’s not something people use consistently to absorb sound.

What Are the Average Ratings for Some Common Materials?

At the low-end of the spectrum, marble is the most common example of a material with a 0.00 NRC rating. It does not absorb any sound. Its reflective properties can make for a pretty noisy room if that is the only material used. That is just one reason why kitchens, generally speaking, do not tend to be that quiet. Marble countertops, tables, and more negatively affect sound absorption.

Drywall isn’t much better, with an average rating of 0.15. Different types of drywall can increase the rating a bit, but drywall by itself does not absorb enough sound for the average person. It is known as pretty cheap material by itself but can provide an opportunity to put other materials behind drywall.

That’s why basic drywall is considered to be too cheap for most home and business construction. It might work for interior walls, but separating other people is a huge problem. If the very basic thickness of drywall is used to separate two apartments, it’s going to lead to some long nights.

Adding carpet to any room will make the NRC around 0.4 to 0.5. This depends on the type of carpet, as thicker options will absorb sound a bit more. Rugs are usually the best option if there is one particularly problematic area.

Anything above 0.5 starts to make a pretty big impact. Ceiling tiles are designed to absorb a good amount of sound, and they average out at around 0.7. This is sufficient for a lot of people unless they really need the glue sticks to be perfect in any room. If that is the case, they might go for panels on the ceiling to help things out.

Speaking of acoustic panels, they usually sit right at 1.0, or slightly below. High-quality acoustic panels make the biggest difference, especially in large spaces where acoustics can be terrible. If a restaurant or church did not use anything to help with acoustics, it would be nearly impossible to have meaningful conversations.

How to Determine an NRC Rating

Unfortunately, it is fairly difficult to measure the NRC Rating of an acoustic product accurately without the help of trained professionals. Educated guesses can be made based on how other products are rated, but that doesn’t do much good when purchasing a product online or in stores. No one will know how well it handles sound until it is used practically.

That’s why companies work hard to do all the NRC Ratings for people beforehand. It’s an industry standard that makes it much, much easier for the shopper to find exactly what it is they are looking for.

Why Is an NRC Rating so Important?

If there is any type of noise problem in a particular space, finding the right sound absorption material can make a huge difference. The NRC Rating speeds up the process, allowing people to find a solution that will make an impact the very first time.

Products with NRC Ratings are important for use in homes, offices, recording studios, gyms, and more. Having more control over sound makes a huge difference.

What Are Sound Transmission Class (STC) Ratings?

The STC rating of a product measures the effectiveness of reducing sound transmission going on between two rooms. A great product will be able to reduce decibels, frequency, and transmission loss. These ratings focus on soundproofing products, while NRC focuses only on absorption.

Some people rely on one rating over the other. Others will use NRC and STC Ratings together to make a decision. It’s not a guarantee either of these ratings will be 100% accurate until the product is set up in a real-world scenario, but it is a great starting point for comparison shoppers.

Just remember that it is very easy to confuse absorption and soundproofing from time to time. While most people want great absorption and soundproofing, the two measurements can provide different results that need addressing.

Counting on the NRC Rating

People are always looking for simplified ways to measure things one way or another. The NRC works very well in allowing a person to understand how much a product absorbs sound, and how much it reflects it. Anything that is designed for controlling sound will have the NRC rating readily available.

Remember that NRC ratings should only be used as a quick way to get rough estimates. For a more precise reading, further tests are needed. This is only going to apply to a small group of people, but it is still important to know and understand.

If it still sounds complicated, NRC Ratings make a lot more sense in practical use. Listen to music in rooms with materials listed above to get hear the real-world difference. In just a small amount of time, most people have a pretty good idea of what to expect while shopping around.

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