NIC stands for Noise Isolation Class. What does this measurement assess?

• A. Heat transfer through walls.
• B. Air leakage through seams.
• C. Structural vibration of floors.
• D. Sound transmitting abilities of a wall construction.

Answer: (D)

NIC measures how well a wall or partition blocks airborne sound from one side to the other. It reflects the sound isolation of the construction—the higher the NIC, the less sound passes through. It is not about heat transfer, air leakage, or structural vibration, which are covered by other performance metrics. So this measurement specifically reflects the wall’s ability to transmit or, more accurately, resist the transmission of sound.