CAS Quarterly

Spring 2018

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66 S P R I N G 2 0 1 8 C A S Q U A R T E R L Y MIXERS CAN HEAR The International Telecommunications Union decided in this period to test meters for broadcast loudness. A grand round robin test was conducted, involving five international test sites, 97 listeners, and coincidentally, 97 items of program content. Ten meters were submitted for comparison testing between what they read and what the listeners heard in a level-matching experiment. As it turns out, the most sophisticated meters didn't do as well as a pretty simple one, which today we call LKFS. L for loudness averaged over a time interval, K for a new weighting curve that rolls off the bass and shelves up higher frequencies to make the metering more like perceived loudness, and FS for relative to Full Scale. When the US came to writing ATSC standards, committee members felt that it would be necessary to repeat this experiment, to be sure it represented American interests as to program material and methods. One test site was enough—the Control Room of the USC Spielberg Scoring Stage (since that time, rededicated to John Williams), six listeners, and 41 items of program material representing a wide range of television audio. You could see this as a confirmation test of the larger one done by the ITU. Only six mixers you ask? Yes, but—among them, they had four Oscars ® and three nominations, 20 Prime Time Emmys ® and five nominations, six CAS Awards and five nominations—and this for only six mixers! "If you build it, they will come" applies. b y T o m l i n s o n H o l m a n C A S WHILE THE STATEMENT OF THE TITLE would be agreed to by practically all CAS members, how do we go about proving it, in a subjective world, with an objective test? During the development of ATSC digital television, the idea came up that rather than referencing Full Scale for a digital system with >100 dB dynamic range (which led to a loudness race in the music business), let's use something like the photographic gray card, a mid-tone reference. From this came the idea of Dialogue Normalization, which was not meant to reduce artistic expression, but rather to make loudness more interchangeable among programs, channels, and commercials.

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