Case study: Maintaining broadcast audio quality during a pandemic

Tall Audio, The Choir, BBC TV

26 April 2021

The TV production sector has had numerous challenges to overcome since the start of the COVID-19 pandemic. High on the list of these is how to maintain audio quality when studios are closed and both contributors and audiences are remote. The CEDAR DNS 8D noise suppressor has proved to be a vital tool in this battle.

One flagship project that used a DNS 8D to overcome its audio problems was the BBC production, The Choir. The idea behind the series was to create "a choir out of all of us", with the participants coming together virtually to sing a song that they had written.

Twelve households took part each week, each using an iPhone for the video plus additional microphones for the audio. According to Alex Wrigglesworth, Sound Supervisor at Tall Audio Sound Services, the audio production was incredibly challenging. While his team found that the iPhone 11 had a good camera, the audio was really tricky, often with equipment fans creating nearby noise, and the on-site crews even had to wrap some devices in tin foil to minimise interference. The audio was delivered to Alex 'live' and, in his own words, he used "a lot of CEDAR noise reduction" to treat it as it came in.

He told us, "We were dealing with a non-ideal situation with different locations using different mics and adapters and having different noise floors, and I had to process this on-the-spot using the DNS 8D and then decide whether each audio stream would be usable after noise reduction. In a normal situation you get the audio right in the first place and the rest is easy, but what we were doing wasn't normal. Also, because of the way the show was structured, the crew would set up the gain structure on the iPhone while someone was talking and inevitably there would be quite a high noise floor. Then someone would start singing and everything changed, which created additional problems."

We asked him how he used the DNS 8D and he continued, "If I'm using a CEDAR DNS 2, I can normally stick it across a group of mics in its auto mode and let it get on with the job. But for this one I had to single out problems on individual feeds, so I was using the detail mode in the DNS 8D to identify problems and pull them out. Sometimes, I could turn the system on and things would sound fine but, when all the locations were coming in, there would always be two or three that needed treating more than the others. I was able to set them up individually, but they all had to be CEDAR'd."

"The hardest thing with CEDAR is not using too much noise reduction. It's a balancing act between keeping the audio sounding natural - you don't want things to sound too dry - and reducing the noise enough to make it usable. I tend to use CEDAR across most of the stuff that I do, whether it's live or pre-recorded, but I don't often use more than around two or three dBs of reduction. If I have to use more than that I start to get slightly worried about what I'm being given. But during this project I definitely had to use more. I couldn't have done it without the DNS 8D."

Other projects that Alex has worked upon include Morning Live (BBC), MotoGP (BT Sport), the Martin Lewis Money Show (ITV), and the Alternative Election Coverage (Channel 4).


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