Sound Transmission Class (STC) is a single-number rating of the airborne sound transmission loss (TL) performance of a constructed assembly measured at standard one-third octave band frequencies.
The higher the STC rating, the more efficient the construction will be in reducing sound transmission within the frequency range of the test.
Outdoor/Indoor Transmission Class (OITC) is a number rating of the sound transmission loss of a constructed assembly tested with lower frequencies to represent sound typical of modes of transportation. OITC is of relevance to designers interested in how effectively their design will shield occupants from sound generated exterior to the structure.
More on sound attenuation.
NOTE: The definitions of terms and terminology herein are rooted in the context of use in the field of construction-related joint sealing in EMSEAL’s experience. They are provided with the intent of offering a fuller understanding of the context of their usage. Any suggestions or questions regarding interpretation are welcome and should be directed to firstname.lastname@example.org. Thank you.