5. In premises larger than 250 m3 for exhibiting films to the public, the electro-acoustic response of chain B must be within the limits of the tolerance curve set forth in Schedules I and II.
The B or final chain is that part of a motion-picture sound reproduction system shown in Schedule III. It begins at the input terminals of the main fader and ends at any position in the listening area for the public viewing of films where sound pressure measurements are taken.