What Does NRC Really Mean? A Practical Guide to Acoustic Ratings

If you've been looking at acoustic panels or room dividers, you've probably come across specifications like NRC 0.40, NRC 0.75 or NRC 0.90.

At first, the number seems straightforward: higher must mean quieter.

That's not exactly how it works.

NRC is useful when comparing sound-absorbing materials, but it is also one of the easiest acoustic specifications to misunderstand. A panel with an NRC of 0.90 does not mean your office will suddenly become 90% quieter, and it doesn't mean the panel blocks 90% of sound.

So what does the number actually tell you?

Let's make sense of it without getting unnecessarily technical.

First, What Is NRC?

NRC stands for Noise Reduction Coefficient.

It's a rating used to describe how much sound a material absorbs rather than reflects back into a room.

That's an important distinction.

Imagine walking into an empty office with concrete floors and glass walls. When you talk, your voice can sound sharp or echoey because much of that sound is bouncing off hard surfaces.

Now imagine adding upholstered furniture, carpet, acoustic panels and PET felt dividers.

Those softer, absorptive surfaces interact with sound differently. Instead of allowing as much sound energy to reflect back into the space, they absorb some of it.

NRC gives us a standardized way of describing that absorption performance.

How Is NRC Calculated?

Sound doesn't exist at just one frequency.

There are low-frequency sounds, mid-frequency sounds and high-frequency sounds, and an acoustic material may perform differently across them.

For NRC, laboratory absorption measurements at four frequencies are used:

250 Hz, 500 Hz, 1,000 Hz and 2,000 Hz.

The absorption coefficients at those four frequencies are averaged, with the NRC value rounded according to the standard methodology.

For example, imagine a material had these hypothetical absorption values:

The average is:

(0.50 + 0.70 + 0.90 + 0.90) ÷ 4 = 0.75

So its NRC would be approximately 0.75.

You don't need to calculate this yourself when buying acoustic products—the test data should provide the rating—but understanding where the number comes from makes it much easier to interpret.

What Does NRC 0.90 Actually Tell You?

This is probably the most important part.

When you see:

NRC 0.90

it does not mean:

This product makes the room 90% quieter.

And it doesn't mean:

This product blocks 90% of sound.

NRC describes absorption, not the overall reduction in noise level that you'll experience in a particular room.

That's why two rooms using exactly the same acoustic material can still sound completely different.

One might be a small carpeted office with an acoustic ceiling and upholstered furniture.

The other might be a large restaurant with concrete floors, floor-to-ceiling glass and a high exposed ceiling.

The acoustic material hasn't changed.

The environment around it has.

A Simple Way to Think About NRC

Rather than thinking:

NRC 0.90 = 90% quieter

think:

NRC helps me compare how absorptive different materials are.

A higher NRC generally indicates stronger average sound absorption across the frequencies included in the NRC calculation.

As a simplified comparison:

These ranges aren't rules for specifying a project. They're simply a practical way to understand the scale.

Why Does Sound Absorption Matter?

Consider a busy open office.

There might be 30 people in the same general area. Someone is taking a call, another group is having a meeting and two employees are discussing a project.

The problem isn't necessarily that any one person is being extremely loud.

It's that sound from all those conversations interacts with the room.

Hard surfaces reflect sound. Those reflections add to the overall acoustic environment and can make speech and background noise feel more noticeable.

Introducing absorptive surfaces can help control some of those reflections.

That's where acoustic wall panels, ceiling panels, baffles and acoustic room dividers come into the picture.

NRC Doesn't Tell You How Much Sound a Panel Blocks

This is where the difference between sound absorption and sound blocking becomes important.

Let's say you put a PET felt divider between two desks.

The felt can absorb sound and help reduce reflections around the work area.

But you may still hear the person speaking on the other side.

That doesn't mean the acoustic material isn't working.

It means absorption and isolation are different jobs.

Sound absorption

Deals primarily with sound reflecting within a space.

Sound isolation

Deals with sound travelling from one space to another.

A lightweight acoustic panel may be excellent at absorbing reflected sound without behaving anything like a fully constructed wall designed for sound isolation.

This is also why we prefer describing PET felt products as sound absorbing rather than "soundproof."

NRC vs. STC

You'll sometimes see NRC and STC mentioned together, which can make them seem interchangeable.

They're not.

NRC (Noise Reduction Coefficient) tells you about sound absorption.

STC (Sound Transmission Class) relates to how well a building assembly reduces airborne sound transmission through it.

A simple way to remember the difference is:

NRC = How much sound is absorbed?

STC = How much sound gets through?

So if you're trying to reduce reverberation in an open office, NRC is relevant.

If you're designing a wall between two private meeting rooms and don't want conversations travelling between them, you're dealing with a sound-isolation problem.

Why Surface Area Matters Almost as Much as the Rating

Here's something that can easily get lost when comparing product specifications.

Suppose you have a very large restaurant and install one small panel with an NRC of 0.90.

It's a highly absorptive material—but it's still one small panel in a very large room.

Now imagine covering a much larger area with acoustic material.

You've given considerably more of the sound in the room an opportunity to interact with an absorptive surface.

That's why acoustic treatment shouldn't be approached as:

"Which product has the highest NRC?"

A better question is:

"How much absorptive material does this space need, and where should it go?"

The NRC rating matters, but so do quantity, dimensions and placement.

Placement Matters Too

Imagine an open office where almost all the noise is coming from a collaborative meeting area.

You could install acoustic material on the opposite side of the building.

It may still contribute some absorption, but that's probably not the most thoughtful way to address the problem.

Putting acoustic surfaces closer to the areas where conversations are happening can often make more practical sense.

This is one reason we like acoustic dividers for open interiors.

They're not restricted to a perimeter wall.

A divider can be placed:

between desks

beside meeting areas

between restaurant tables

around reception spaces

between different working zones

You're introducing absorption into the area where people are actually using the space.

Thickness Can Change Acoustic Performance

Two PET felt panels can look very similar while having different acoustic characteristics.

Thickness is one factor.

A thicker panel doesn't automatically mean "twice as good," but changing the thickness of an acoustic material can change its absorption performance.

Installation conditions can also influence results.

For example, a material mounted directly against a surface may perform differently from the same material installed with an air space behind it.

That's why, when comparing NRC values, it's useful to know how the material was tested rather than comparing the number in isolation.

What About PET Felt?

PET felt has become a popular material for architectural acoustic products because it gives designers a useful combination of function and appearance.

Its fibrous structure allows it to absorb sound, but unlike some traditional acoustic treatments, it can also become part of the interior design.

PET felt can be:

CNC cut into patterns

produced in different colors

used as privacy screens

made into room dividers

installed as wall or ceiling treatments

That means you don't necessarily have to choose between adding an acoustic material and creating an attractive interior feature.

For an office, for example, a PET felt divider can help define individual work zones while also adding an absorptive surface to an otherwise open room.

What NRC Should You Look For?

There's no single NRC number we'd recommend for every project.

Instead, start with the actual problem.

If you're working with a small office that already has carpet, acoustic ceiling tiles and soft furnishings, its needs may be very different from a restaurant filled with glass, tile and concrete.

Ask:

Is the room noticeably echoey?

Where is most of the noise coming from?

How large is the room?

How much absorptive material is already there?

Are you trying to reduce reflections or block sound between rooms?

How much acoustic surface can realistically be added?

Once those questions are answered, NRC becomes much more useful.

You're no longer looking for the "highest number." You're using the rating to compare materials that could actually work for the project.

How This Applies to Acoustic Room Dividers

For an acoustic room divider, NRC is only one part of the decision.

You should also think about what the divider needs to accomplish visually and physically.

For example:

Need more privacy?

Choose a design with fewer or smaller openings.

Want to maintain an open feel?

A more decorative cutout pattern may allow light and visibility through the divider.

Need flexibility?

A freestanding configuration may make more sense.

Want an architectural installation?

Consider a fixed or floor-to-ceiling divider.

Primarily concerned about acoustics?

Look at panel thickness, tested acoustic performance, the amount of felt being installed and where the divider will sit in relation to the noise source.

That's a much more practical approach than choosing a panel based solely on NRC.

One Number Can't Describe an Entire Room

This is probably the biggest takeaway.

NRC is useful.

It's standardized, widely recognized and gives us a convenient way to compare sound-absorbing materials. But it's still one number describing one characteristic of a material under specific test conditions.

It can't tell you exactly what your restaurant will sound like on a Friday night.

It can't tell you whether employees will hear a conversation happening across the office.

And it can't tell you how many acoustic dividers your project needs.

Those answers depend on the room itself.

When we're looking at an acoustic project, we prefer to think about NRC as one piece of a larger picture:

Material + thickness + surface area + placement + room conditions + installation = overall acoustic result.

That's ultimately a much more useful way to choose an acoustic product.

NRC and CraftivaArt PET Felt Dividers

CraftivaArt's PET felt acoustic divider options offer NRC performance ranging approximately from 0.40 to 0.90, depending on the material thickness and installation configuration.

The panels are designed to combine sound absorption with something that is just as important in many commercial interiors: space division and privacy.

Rather than adding a conventional acoustic panel simply because a room is noisy, a PET felt divider can become part of the layout itself—separating workstations, defining meeting areas, dividing restaurant seating or creating privacy within an open commercial space.

And because the panels are available in multiple colors, patterns and installation configurations, the acoustic treatment doesn't have to feel like an afterthought.

It can become part of the design.