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.