What is the NRC requirement for walls in enclosed offices, conference, or teleconferencing spaces?

• A. 0.9 on all walls
• B. 0.7 on 25% walls
• C. 0.8 on all walls
• D. 0.8 on 25% walls

Answer: (D)

In spaces where people will be speaking and there’s a need for clear conversations—like enclosed offices, conference rooms, or rooms used for teleconferencing—the acoustic goal is to damp sound reflections so speech stays intelligible and private. The requirement is that at least a portion of the wall surfaces have strong sound absorption. Specifically, at least 25% of wall surfaces must achieve an NRC of 0.8 or higher. An NRC of 0.8 indicates high absorption across the mid to high frequencies typical of human speech, which helps reduce reverberation and improves privacy without having to cover every wall with absorptive material. This 25% threshold balances effectiveness with practicality and cost. Options with higher or universal absorption are more stringent than necessary, while a lower absorption rating would not provide the desired improvement in speech privacy and intelligibility.