What is NRC? What NRC value is suitable for a meeting room?

What is NRC? What NRC value is ideal for a meeting room? 

NRC stands for Noise Reduction Coefficient, a standard rating used to measure the "sound absorption" performance of a material. It is calculated by averaging sound absorption coefficients at frequencies of 250, 500, 1000, and 2000 Hz, which are the main frequency ranges of human speech.

The NRC scale ranges from 0.00 to 1.00.

• NRC close to 0: The material absorbs almost no sound; nearly all sound is reflected, such as glass, bare concrete, and plaster walls (NRC around 0.05).

• NRC close to 1: The material absorbs almost all sound, with very little sound reflection.

Simply put, if a ceiling tile has an NRC of 0.60, it means that panel absorbs approximately 60% of the sound energy hitting it, while the remaining 40% is reflected back into the room.

Why is NRC important for meeting rooms?

Meeting rooms are spaces that primarily rely on "speech clarity." If the surfaces in the room are hard materials that reflect a lot of sound, such as glass, glossy tables, or standard plain gypsum ceilings, speech will bounce back and forth, causing reverberation. This makes it harder for listeners to catch details, especially during video conferences where microphones also pick up the echo, making it even harder for participants on the other end to understand.

Choosing ceiling or wall materials with a sufficiently high NRC rating is therefore a key variable that allows meeting rooms to have clear sound without having to speak louder or repeat meetings due to missing information.

What NRC rating is suitable for each type of meeting room?

The appropriate NRC rating varies depending on room size and the level of speech clarity required. Generally, the guidelines referenced in acoustic design are as follows:

These figures serve as a basic guideline. In practice, the NRC value of a material alone does not always guarantee results, as other factors must be considered together.

Other factors affecting acoustics besides the NRC rating

• Surface area of sound-absorbing materials installed No matter how high an NRC material is chosen, if the installation does not cover sufficient area relative to the room size, it may not yield the expected results. It is generally recommended that sound-absorbing surfaces cover at least 25-50% of the total surface area in the room.
• Room volume and shape Rooms with high ceilings or special geometries allow sound to travel further before hitting a surface, requiring corresponding calculations for greater absorption area.
• Other surfaces in the room Glass tables, tile floors, or exposed concrete walls are all reflective surfaces that must be factored in alongside sound-absorbing surfaces, rather than looking at the ceiling alone.

In other words, the NRC value on product specifications is a great starting point for material selection, but designing a space for true speech clarity in a meeting room should be calculated together with surface area and room characteristics by acoustic specialists.

Acoustic ceilings tailored for meeting rooms from Trandar Acoustics

For general meeting rooms requiring reverberation reduction and enhanced speech clarity, mineral fiber acoustic ceilings Trandar AMF Mercure with an NRC of 0.60 are widely used in Grade A office buildings because, beyond sound absorption, they also meet fire safety standards, offer high humidity resistance, and feature a smooth, beautiful surface ideal for office applications.

For large meeting rooms or spaces requiring exceptionally higher NRC values, such as video conference rooms or high-capacity seminar rooms, the Trandar Acoustics team can assist in calculating the appropriate sound-absorbing surface area for the actual room size and recommend material grades to meet your desired NRC requirements.

If you are planning to design a meeting room and want to know what NRC value your room needs, feel free to chat with the Trandar Acoustics team. We are happy to help calculate and recommend the most suitable materials.