ATSC A/85 is the US broadcast loudness recommendation, given legal teeth by the CALM Act, which in 2012 made it illegal for television commercials to be louder than the programming around them. Like its European cousin EBU R128 it is built on ITU-R BS.1770 measurement, but it targets -24 LKFS (equivalent to LUFS) and frames its guidance around the 'anchor' loudness of dialogue. Its practical effect is the one viewers feel: ads no longer blast you when the show cuts to break. A/85 governs how stations and content providers measure, normalize, and pass loudness metadata through the broadcast chain.
