Public Radio Satellite System adopts new standard for audio levels

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The Public Radio Satellite System adopted standards Thursday intended to normalize audio levels among the programs it distributes to stations.

PRSS adopted an audio measurement standard using a number to denote audio levels, instead of the longtime industry standard of peak meters. Decibel measurements provided by meters are largely subjective.

The loudness unit adopted by PRSS is used by organizations around the world. Because PBS also uses it, joint licensees can now rely on a single standard, which will simplify operations, according to the PRSS working group that approved the change.

NPR, American Public Media and PRSS staffers began working on developing the standards in the spring after engineers discussed the problem at a conference in April. A study found that shows distributed via PRSS varied widely in volume, which could prompt listeners to tune away. About half of PRSS content examined by the working group deviated from the distributor’s standards for consistent volumes.

The group agreed to adopt a standard of -24 LUFS, or Loudness Units Relative to Full Scale, allowing for deviation of plus or minus 2 loudness units from -24 LUFS. Stations that haven’t switched to loudness meters should keep audio peaks at below -3 decibels.

PRSS has not set a date for compliance but has started monitoring content, said Steve Densmore, NPR director of broadcast operations. PRSS wants to work with producers and engineers toward providing the best experience for listeners and will offer feedback throughout the transition, he said.

“This is going to be an educational process,” Densmore said.

“Distribution will take an active role in communicating how everyone is doing,” said Chris Nelson, NPR director of technical strategy. “So producers will know exactly how they’re measuring up.”

PRSS will announce the change via ContentDepot messaging, social media, emails and newsletters. A January webinar will cover the issue, and PRSS reps will discuss the new standards at the Public Radio Engineering Conference next April.

  • Adam Ragusea

    This is a great first step, a no-brainer. I’ll be interested to hear more about the enforceability of the standard.

  • ArtStoneUS

    Will stations apply the same loudness standard to their sponsorship announcements and pledge drives?

  • Jim Wilke

    I’m unhappy to hear public radio & tv stations getting into the loudness wars, but from the sound of it many are. Ear fatigue sets in for me when the dynamic range is only a few db up or down and THAT could prompt me to tune away. It’s such an unnatural sound.

  • Aaron Read

    Jim – actually this is a battle AGAINST the loudness wars. The point of adopting the LUFS standard is to fight against the problem of dozens of different producers churning out content that is wildly different in perceived loudness. Check out that link “began working on” in the story above to see what I mean. And +/- 2 LU is not the same thing as +/- 2dB (yes, that would be some hideously over-compressed audio). The goal of adopting the LUFS standard is to keep perceived loudness *consistent* without narrowing dynamic range too severely that it causes listener fatigue. The consistency is key, so people don’t have to constantly adjust their volume knob.

  • Aaron Read

    ArtStoneUS – I can only speak for my station, but yes – that will be our goal. As part of a tangentially-related studio overhaul project, I’m having our new AoIP mix consoles use LUFS meters and I’ll be training the staff on how to use them to hit the -24 LUFS sweet spot. You’re hitting the nail on the head, though – it certainly will help if all national content standardizes on -24 LUFS but it’s only half the battle; the individual member stations have to do for their local content, too.