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 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.

Links:

1. ASTM International:
2. Viraconsulting Glossary: