Swedish Radio to implement loudness controls29 May 2014
Loudness normalisation is to be introduced on all radio broadcast platforms used by Swedish Radio (SR). Sweden’s public broadcaster has tested both hardware and software meters working to the EBU R128 standard at -23 LUFS (Loudness unit relative to Full Scale), as used by European television services.
SR sound engineer and producer Bosse Ternström says the new operational practices will “probably” be implemented in steps starting in either the third or fourth quarter of this year and be focused on production. “We have already performed all the tests we need internally and subsequently we are ready to implement,” he explains. “At the moment we are scanning SR for all the different places and circumstances where loudness meter is needed.”
Ternström adds that this survey process includes determining whether the meter should be hardware or software, where in in the chain it will be used and if there is time to batch-correct files to R128. “The strategy is to implement loudness metering in production, as that’s the only place and way we can take true advantage of R128,” he explains. “Later in the chain it will just be a static gain change, so production is the way to go, with logging capacity further down the audio chain for feedback or, God forbid, correction.”
While NRK Radio and commercial DAB broadcasters in Norway are working to a loudness target of -15 LUFS (see feature), the goal recommended by the EBU PLOUD group for TV – and by extension radio – is -23, which is being followed by SR. “It is a huge mistake to deviate from that [because from our perspective] -23 LUFS for all in-house [work] is clear and used,” Ternström says. “When it comes to the transmission/emission stage PLOUD has specified an ‘offset’ for FM of 6.7 dB. Then the levels will be even in all circumstances between FM and digital. If you deviate from -23 to -15 we have shown that for every 24 hours, about two hours of your programming will be, or need to be, limited.”
SR has also worked with the EBU and PLOUD to use R128 as FM mask, instead of MPX power and ITU 412-9 compression. Ternström says that initial trials have shown that R128 “will be beneficial for broadcasters mainly because of the K-weighting curve used and the fact that we will create something like a one to one paradigm throughout the audio chain from production to the receiving end”.