What does STC mean?
STC stands fro Sound Transmission Class. This rating is used to compare the acoustic isolation of different materials. The Method used to calculate the STC rating is (ASTM E413) A general idea of how this method works is: 1) Their are 2 rooms, a “source” room which contains a loudspeaker and a “receiver” room which contains a microphone. Between the two rooms is an opening usually sized 8ft by 9ft. 2) In decibels (dB), the sound is recorded from in 1/3-octave bands from 125 Hz to 4000Hz 3) The next step is to record the sound again (same process as above) in decibels (dB) with the material (or materials) completely covering and sealing the opening. 4) Then, the difference between the before and after measurements are calculated and recorded. These measurements are the transmission loss or “TL” of the sound. 5) Lastly, (this may be confusing for some) the transmission is drawn on a graph of 1/3-octave and center frequency versus level in decibels. The STC is the measured curve compared
