What do STC ratings and other sound measurement terms mean?
Sound Transmission Class (STC) is an expression of Sound Transmission Loss (described below under STL) as a single number which indicates performance over a selected range of sound frequencies. The higher the STC, the more efficient the partition or floor will be for reducing sound transmission in most environments. The STC rating for SoundStop® is 23. STL is a measure of the sound insulating efficiency of partition or floor construction, expressed in decibels. It represents the reduction of energy which occurs when sound is transmitted through a partition or floor. Resulting noise reduction depends on the type of sound and construction design and materials. Intensity of sound is measured in units of decibels (dB). Higher sound intensity yields a higher decibel number. Noise Reduction Coefficient (NRC) is the accepted index of materials sound absorbing effectiveness. NRC is the mathematical average of four coefficients of absorption-at 250, 500, 1000 and 2000 cycles per second-expresse
