Sound transmission class (stc)

A single-number rating obtained by classifying the measured values of Sound Transmission Loss in accordance with ASTM Standard E 413, ?Classification for Sound Rating Insulations?. It provides a quick indication of the performance of a partition for certain common sound insulation problems. To determine the Sound Transmission Class (STC) in conformance to the ASTM E 413 (lSO 71 7/1) one must slide the STC contour along its Y-axis of the graph on which the transmission loss curve is plotted until the following conditions are met