ISO 2969:2015 specifies the measurement methods and characteristic electroacoustic frequency response of the B-chain of motion-picture dubbing theatres (mixing rooms), screening rooms, and indoor theatres whose room volume exceeds 125 m³ (4,414 ft³). It is intended to assist in standardization of monitoring and reproduction of motion-picture sound in such rooms. The goal is to have constant perceived loudness and frequency response from installation to installation, and from position-to-position within an installation. This International Standard does not cover that part of the motion-picture sound system extending from the transducer to the input source audio selector.