The opening ceremony of the Beijing Olympics demonstrated that dialog normalization is a thing easier said than done. Viewers at a sports bar in Pasadena, Calif., were deprived of the program audio because the ads were so much louder, and tended to drown out the screens carrying a football game favored by regulars.
Dialog normalization, or “dialnorm,” refers to the limits on volume variations set by the FCC. Audio volume may drastically vary between channels, programs and ads. Dialnorm devices are set at a certain level--usually around -23 to -24 dB--to reign in extreme variations, but the process is still much more complicated than placing yet another piece of gear in the distribution chain. The use of Dolby E encoding can complicate the process, depending on how it“s implemented. The number of feeds, passes, mics, venues, conversions, transmission hops, the settings on set-tops and receivers, and placement of speakers, can all impact how audio is ultimately experienced.
Advertisers are notorious for delivering extra loud commercials, because even though they annoy, they get people“s attention. Broadcasters typically request material at a certain loudness level, but they get what they get. The price of an Olympics minute has been reported to run at around $1.5 million. Broadcasters have previously pointed out that someone spending millions with a network is unlikely to receive a lecture in dialnorm.
With regard to the Olympics opening ceremony, the problem didn“t appear to be specific to advertisers. Promos for the local affiliate, KNBC, were as loud as everything else in the commercial breaks. The volume discrepancy also seemed limited to Friday night“s coverage.
An engineer watching the event on the East Coast said he noticed that announcers Matt Lauer and Bob Costas were barely audible during the ceremony. He said he thought the problem was how their voices were routed through the 5.1 surround sound channels.
“Suppose you have nice surround sound,” he wrote. “Now you add a commentator. If it“s done right, the commentator appears in the center channel, or some weighted combination of the channels. If done wrong, however, the commentator could appear in the left front channel in one polarity and in the right front with a different polarity. To people listening in surround, this might sound a little odd but not tragic. To people listening in mono, however, the commentator would become very soft, if audible at all. Or the center channel could have an improperly set compressor, so it gets driven down more than the other channels. Commercials, mixed differently wouldn“t have that problem. That“s what I thought I detected in the opening ceremonies.”
An engineer familiar with NBC“s Olympics operations said 5.1 wasn't the culprit, but that the dynamic range of the opening ceremonies was particularly challenging.
“The loudest sounds and softest sounds were very widely spaced,” he said. “The announcers were about equal to the dialnorm value that was being sent, but were indeed slightly low on average, [and] some of the commercials were kind of loud.”
Wide dynamic ranges aren“t necessarily a bad thing, he said.
“It adds life to the audio and allows TV to compete with DVD and film. The challenge is getting used to the new “roominess,“ like moving from a tiny apartment to a mansion. You might need to arrange the furniture differently.”
Achieving the proper dialnorm level has required audio mixers to adjust how they assess what they see on loudness and VU meters, he said.
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