Whats an STC?
STC stands for ”Sound Transmission Class.” This is a single-number rating that can be used to compare the acoustical isolation of different barrier materials or partition constructions. The method used to determine the STC of a material or partition type is complicated. The following is a basic description of the methods covered in much more detail in ASTM E413: The method to determine STC is conducted using two test rooms: a ”source” room and a ”receiver” room. The source room will contain a full-range test loudspeaker. The receiver room will contain a microphone, which is connected to sound-measuring devices. There is a nominal opening between the two rooms – usually about 9′ wide by 8′ high, but can vary in accordance with the standard. The first step is to measure the sound transmitted from one room into the other through the opening. The sound is measured in decibels (dB) in 1/3-octave bands from 125 Hz to 4000 Hz. The next step is to ”plug” the opening with the material o
