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Radio – the loudness war’s second front

Kevin Hilton 28 May 2014
Radio – the loudness war's second front

Loudness has been a niggling problem in broadcasting for years. In under a decade, new standards and equipment have been developed to tackle this tricky technological irritant in television. But those behind these advances agree that the so-called loudness war is nowhere near over, with radio as the next challenge.

The EBU PLOUD working group, which produced the R128 loudness standard being used in an increasing number of European countries to produce more consistent TV audio levels, is now looking at how to bring similar uniformity to radio. Attempts were made in TV to deal with loudness before the ITU produced the first international standard – BS 1770 – in 2006. In a similar way some radio broadcasters are now implementing operational guidelines to achieve consistent levels before specifications are agreed for the medium.

Norway has taken an early, and almost unsung, lead in radio loudness. Public broadcaster NRK and the country’s two commercial DAB operators came to a “gentlemen’s agreement” in February 2012 that they would all work to a set target level, monitor each other’s outputs and advise if there were any deviations, something they are doing without involving the broadcast regulator.

Details of this scheme were given during the Radio Academy TechCon in Salford last October. Bjorn Aarseth (pictured), a senior engineer with NRK, outlined the broadcasters digital platforms, including DTT, DVB-S, DVB-C, IPTV and IPTV, saying that all offer radio services as well as video. The country also has established DAB networks but is planning a move to DAB+, with an analogue switch off in 2017. Aarseth says this will happen if, by next year, 50 percent of radio listening is through digital; if not the final switchover will be in 2019.

Digital radio sales are booming in Norway, particularly among older listeners, but, as Aarseth noted, broadcasts are victims of the music loudness war. This, he said, was inherent because of modern digital production techniques, meaning tracks tended to hit the same maximum level all the time – producing what is known as a “loudness sausage” because the waveform is thick and tubular. “[But] very many radio channels are into sausage production as well and compress the levels heavily,” he explained. “What we wanted to do was loudness normalise all the programmes so that when our listeners switched between channels they should have the same level.”

R128 forms the basis of the agreement between NRK and its commercial counterparts but instead of the -23:LUFS (Loudness Unit relative to Full Scale) target specified for TV – which was generally assumed by PLOUD would be the goal in radio – the Norwegian broadcasters are working to -15. “This has caused a lot of grief from the EBU; they don’t like it,” Aarseth observed, “but there is a reason for that high level.”

Aarseth explained that radio content is “very different to TV” and that in general “listeners are everywhere, not on the couch with the clicker like TV viewers”. Another consideration was that the radio audience “might need a lower dynamic range”. But the primary reason behind selecting -15 was very specific to Norway, its terrain and the number of people listening in their cars.

The country is known for its mountainous regions and tunnels. When someone listening to DAB drives into a tunnel the radio will re-tune to FM, which is available through leaky feeders. “We did a study on FM and DAB combined radios and saw that -15 on DAB would match the FM level,” Aarseth commented. “That was very important because… if the levels rise 8dB or something, that would be a traffic hazard. So that’s the main reason for -15.”

The chair of PLOUD, Florian Camerer, has said he hopes that when Norway moves to full DAB+ transmission and switches off FM the target level will be reduced to -23. This seems unlikely right now; during his presentation Aarseth said -15 worked well not just for DAB and FM but also was close to the -16 of internet services such as iTunes. “Will we go back to -23?” he asked. “I don’t think so. It may change but by not as much as 8LUs.”

Another Nordic broadcaster, Swedish Radio (SR), has carried out internal loudness monitoring and normalisation tests, with the intention of implementing specifications for production by the end of this year (see news story). SR is working to -23, which sound engineer and producer Bosse Ternström says is “clear and used” for all in-house operations.

In the UK, the BBC has been testing loudness equipment on a range of programming across its radio networks, again aiming at -23. Among the stations currently using R128 is BBC Radio 4extra; this broadcasts archive comedy and drama programmes from the 1940s to the present day, so producing a consistent output between that, continuity announcements and indents is seen as important. Principal technologist Simon Tuff comments that loudness in this context “is a challenge for us” because it is not yet a unilateral decision on how to approach the issue.

Back in Norway the gentlemen’s agreement appears to have worked. Bjorn Aarseth concluded his presentation by saying the listeners were happy because there had been no complaints about loudness in the 18 months the arrangement had been in place. Which, given the propensity radio aficionados have for writing letters or emails, is something.

tech.ebu.ch/groups/ploud

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