reduction coefficient

The tile panels should be a least three-quarters of an inch thick and have a noise reduction coefficient rating of .65.

Acoustics: Contractors and builders often mention the noise reduction coefficient, or NRC, when discussing the acoustic performance of insulation.

"Noise Reduction Coefficients (NRC) for Common Building Materials."

The Noise Reduction Coefficient (commonly abbreviated NRC) is a scalar representation of the amount of sound energy absorbed upon striking a particular surface.