Outdoor–indoor transmission class
This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (April 2018) (Learn how and when to remove this template message)
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.