Live From NAB: DTV Audio Group Conference Focuses On Loudness Reality

If you thought the broadcast-loudness issue was settled, think again. The leadoff round of presentations at the DTV Audio Group’s NAB Show meeting, which took place on Sunday, focused on exactly that. Among the presentations, the process by which program loudness can be monitored 24/7 included measurement of the differentials between stations’ average loudness and the accepted dialnorm level of -24 LKFS has narrowed considerably, which reportedly was down to as little as half a decibel.

The results of weekly surveys are coded with the responses green (compliant), yellow (borderline), and red (out of compliance). A national program of reporting is still being put into place, but that the broad range of anomalies is small and generally limited to less than 2 dB. A self-certification template that stations can use to report and post on their Websites has been developed.

The larger picture focuses on technical compliance versus the actual user perceptual experience. However, the process of trying to smooth the audio experience out for viewers can lead to over-use of dynamic limiting, which can decrease the overall quality of the audio.

That set up subsequent presentations that reminded attendees that there are still two very different perspectives on the issue. Ken Hunold, senior broadcast applications engineer at Dolby, used an A/B showing of a Yankees-Blue Jays game segment, first with no audio-limiting processing applied, then with limiting processing. He used graphs to illustrate how starkly processing can truncate audio dynamics, concluding, “Dynamic range is a separate issue from loudness processing. … And content should not be processed to stay within the comfort zone.”

The subsequent presentation, by Linear Acoustic President Tim Carroll, didn’t disagree but put its emphasis on the viewer experience, citing the same excerpt from the game to point out that, as a result of the processing, viewer complaints about loudness inconsistencies decreased: “That second clip [of the processed audio] through a 2-in. television speaker would sound respectable.”

He said went on to point out that conventional audio processing is reliable, available and cost-effective and that it achieves its primarily aim: avoiding complaints and FCC fines. Audio quality in the form of wider dynamics is, he said, “icing on the cake” at the moment but can be achieved as application of processing becomes more refined.

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