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Progress on Pubcaster Audio Level Bounce Issue

Working group hopes to get compliance with EBU audio loudness standard

A working group dedicated to resolving varying audio levels in content distributed to public radio stations has figured out a game plan.

The group is comprised of representatives from National Public Radio’s Public Radio Satellite System, NPR and American Public Media. NPR and APM together have been discussing the audio level inconsistency issue with content creators and distributors.

I last wrote this summer they had surveyed stations to gather information about the need to achieve consistent audio levels between and within programs. NPR Director of Technology Strategy Chris Nelson and NPR Labs Technical Researcher Alice Goldfarb reviewed some 6,000 audio files to get a sense of the issue. They found audio levels that were “drastically different” from source to source, according to Nelson, including a 20 to 25 dB difference between some programs within PRSS.

Now, the working group is going to ask those involved with creating and distributing both broadcast and streamed programming to comply with the EBU loudness standard. “We’re looking for a loudness figure in the program of –24 LUFS (which stands for Loudness Unit relative to Full Scale) as measured on an ITU-BS-R 1770-3 meter, says NPR Director of Broadcast Operations Steve Densmore. LU is similar to dB, in engineering parlance.

The standard is: –24 LUFS, ±2 LU, audio peaks <–3 dBTP. “The whole idea is to enhance the listener experience. By targeting a figure, you’re asking the producer to aim for that,” says Densmore.

The point is, once the listener adjusts the volume control (or touches the screen) to their preferred level, they wouldn’t need to touch it again. For example, for segments within a show, if adhering to the standard, “won’t have one segment way louder than the others, making the listener have to reach for the volume control,” he tells me.

The industry is moving away from traditional peak VU meters to measure sound and towards newer loudness meters that give a numerical reading of the perceived volume of audio content. “The idea is to measure sound the way we hear,” says Densmore. NPR added new loudness meters to its in-house broadcast studios in April and has seen improved audio level consistency across shows, according to Nelson.

The working group introduced the standard last week to the Distribution/Interconnection Committee, a subgroup of the NPR board that oversees the PRSS. The group is now working to get the word out and PRSS plans to conduct a webinar on the topic for producers sometime in mid-January.

The plan is to begin monitoring all audio, either as an uploaded file or stream, fed to the ContentDepot, and communicating with program producers about how to hit the mark. Discussion is ongoing among the working group about what kinds of software and hardware is necessary to achieve consistent audio levels.

When asked providing the necessary tools to producers, experts say: “Our plan right now is to educate, monitor and provide feedback. Part of the education process is to provide a list of tools that are available.” Some of the tools are affordable and others are not, however the group doesn’t have the resources to buy tools for producers.

Given that, they tell me: “Many producers and producing stations may find they already have what’s needed to produce audio compliant with our announced standard. If we find the goal of uniform loudness throughout the system is not achievable within the current planned effort, we’ll look around for more options.”