Outdoor–indoor transmission class

Outdoor–indoor transmission class (OITC) is a standard used for indicating the rate of transmission of sound between outdoor and indoor spaces in a structure. It is based on the ASTM E-1332 Standard Classification for the Determination of Outdoor–Indoor Transmission Class. An alternative similar standard for determining the rate of acoustic isolation of a separation between spaces is Sound transmission class (STC). While STC is based on a noise spectrum targeting speech sounds, OITC utilizes a source noise spectrum that considers frequencies down to 80 Hz (Aircraft/Rail/Truck traffic) and is weighted more to lower frequencies.