Define Noise Criteria (NC).

• A. The sound pressure limits for a room.
• B. The color of the room.
• C. The energy consumption of HVAC.
• D. The architectural acoustics rating system.

Answer: (A)

Noise Criteria defines how loud the background noise inside a space can be, using a single NC rating derived from a set of curves across different frequencies. In practice, you measure the room’s sound pressure levels in octave bands and compare them to the NC curves. The highest curve that the measurements don’t exceed becomes the room’s NC rating. This concept matters because it directly targets the interior acoustic environment—guiding HVAC and other noise sources to stay within comfortable, intelligible levels for occupants. The other options describe unrelated aspects, such as color, energy use, or a broad acoustics rating system, rather than the specific interior noise level target that NC provides.