Surround sound has been a contentious issue in professional audio for decades. There is little dispute about what multichannel audio has brought to the cinema but in broadcasting there are still doubts about its true value, despite the continuing efforts of broadcasters like Sky to make surround a key part of the overall viewing experience.
SoundField microphones have been at the centre of such discussions since the early 1970s, when surround sound music - in the form of quadrophonic - was supposedly the next big thing. It was also the time Michael Gerzon proposed Ambisonics to deliver spatial audio, with a sensation of height and depth as well as width and length.
More recently SoundField mics have played a major role in delivering surround sound in sport. Many European broadcasters, notably Sky, have installed SoundFields at major sports venues to provide multiple audio channels to go with high definition pictures. Despite this high profile use surround sound equipment still has a specialist, almost arcane image of being slightly outside the mainstream of professional broadcast audio.
That perception could change, for SoundField at least, now that the technology is part of the TSL Professional Products Limited (TSL PPL) range. Known for its audio monitoring and processing equipment, TSL PPL bought the SoundField brand and technology just before last year's IBC, since when it has been integrating the products and remaining staff into its operations.
During this year's NAB TSL PPL promoted the benefits of surround sound - and by extension SoundField - for broadcast sports. It launched a new product, the X-1 single unit surround-to-stereo/stereo-to-surround upmix/downmix processor, and highlighted the DSF-B surround mic package. This comprises a DSF-2 mic, DSF-2 controller and a DSF-3 processor, with the option of the DSF-3 control app.
Pieter Schillebeeckx joined SoundField in 2000, later becoming head of R&D. He joined TSL PPL and as product manager for SoundField focuses on product and brand development, supported by the company's R&D and product management teams.
Live broadcast is the principal market for SoundField and Schillebeeckx sees maintaining audio quality between different locations and varying skill sets a major challenge in this sector. "The right tools and approach can really help in creating a consistent sound quality across a wide range of venues and engineers," he says. "Broadcasters are using a wide range of approaches but all are aiming for realistic 'you are there' surround ambiences, simplicity of use, guaranteed downmix compatibility and consistent and repeatable results."
In capturing surround sound engineers have the choice between single source microphones, including SoundField, Core Sound TetraMic and the DPA 5100, and multi-mic arrays such as those offered by Schoeps.
Schillebeeckx regards multiple capsule set-ups as the traditional approach but says they have drawbacks in terms of set-up, trouble shooting and de-rigging, as well as on the technical side. "Such arrays usually produce audio that suffers from phase incoherency creating several problems when the 5.1 audio has to be 'collapsed' to create a stereo soundtrack for broadcast over SD or legacy networks," he says.
Naturally Schillebeeckx sees single source surround mics as the more efficient and higher quality option, particularly as some broadcasters and facilities are already beginning to look at extended forms of audio at a time when 5.1 is still not widely established for either standard definition or HD TV. The initial driving force was 3D but that format could be superseded by Ultra HD/4k, with set-ups from 7.1 to 22.2 the possible audio companions.
"5.1 was the answer to HD TV, but with the advent of 3D TV people are starting to ask questions about where next for broadcast audio," Schillebeeckx comments. "As is always the case, the cinema world is starting to evolve first and it looks like they are set to introduce 3D audio to the mainstream, with platforms such as Dolby Atmos, DTS MDA, Auro 3D and Iosono 3D all vying for position. Introducing 3D audio to live broadcast is a huge challenge and will take some time before we will start to see first implementation. There are three aspects to the challenge. First of all we need to find a way of producing 3D audio live - which ever the format - while maintaining downmix compatibility with 5.1, stereo and mono. Secondly we need to get it to the consumers, so we will need a transmission delivery format. Thirdly consumers need to have the means of playing back 3D audio in the home, either over loudspeakers or headphones."
All those extra loudspeakers may not appear in many homes - even with the promise of immersive sound - but there's more than a good chance mics like the SoundField will continue to be at the starting point for an increasing amount of TV audio.