Tech Focus: Immersive Audio, Part 1 — A Toolkit Focused on Capture

Manufacturers are making the mics more accessible and easier-to-use

Conversations around immersive audio for broadcast have a tendency to focus on the outputs: mostly, the number and placement of loudspeakers, especially the four overhead. With Dolby Atmos the dominant immersive-audio format in the U.S., it’s usually a foregone conclusion. However, getting sound into the immersive machine and processing its audio is a more complicated proposition. Microphones to capture it and consoles to process and mix it offer a small but growing array of increasingly necessary options. This month’s Tech Focus looks at both, starting with microphones.

Multichannel Mics

The 2024 Paris Olympics were a case study in immersive capture. NBC Sports deployed 3,680 microphones, including multichannel mics, as part of its immersive-sound strategy to, as Olympic Broadcasting Services (OBS) Senior Manager, Audio, Nuno Duarte described it at SVG Europe’s Sports Audio Summit 2024 in November, “provide a consistent product across every sport, all in 5.1.4, for two weeks straight.”

Interest in the multichannel-microphone category is accelerating, says Joel Guilbert, audio specialist, Dale Pro Audio. Citing several examples, including the Voyage Spatial Mic and Shoeps ORTF-3D array, he points out that network capabilities are making these multi-capsule mics easier to manage.

“We’re seeing more traction with [Power-over-Ethernet]-equipped multichannel mics,” he says. “We see this as coming from a number of fronts. One is that, with Dante and PoE connections, it’s more plausible to connect four-plus mic capsules without having a massive snake or one with tricky smaller connectors. Also, more and more network infrastructure is available. Camera CCUs and most consoles have some kind of Dante connectivity, or most trucks or facilities have some kind of fiber available to use. The necessary accessory items are becoming available without being super-specialty items. We’ve put together kits with solid, relatively off-the-shelf PoE injectors with fiber converters for pretty low cost. These tools all make it easy to work with these [kinds of] mics in a real-world environment.”

Single-Point and Multichannel Approaches

DPA Microphones 5100 mobile surround microphone

An early stalwart of the category, DPA Microphones 5100 mobile surround microphone is a self-contained plug-and-play solution. It was introduced in 2008 for 5.1-audio capture (priced at $3,780) but has been deployed in immersive applications as well. Among its applications for sports are Winter Olympics ice skating and Wimbledon Court 1 in 2023.

However, according to DPA Global Support and Business Development Manager Paul Andrews, use of multiple single-point microphones in arrays, the original technique for capturing surround sound, remains a valid approach to capturing immersive sound as well, offering more-flexible configurations. “Some of our users — Sky Sports, for instance—prefer using single-channel microphones in multiple places to get a more immersive field than just [a single multichannel microphone] might provide.”

But, even within those arrays, he points out, the multichannel 5100 has been used to provide the four height channels of the Atmos format. “There are a number of combinations [of single-point and multichannel mics] you can use to achieve immersiveness, depending on the kind of sound you want.”

It’s All About Technique

That’s also how Sennheiser envisions its new MKH 8030 ($1,499) figure-8 polar-pattern microphone. The latest in the 8000 series are being deployed for immersive capture.

Sennheiser MKH 8030

“For sports,” says Brian Glasscock, project manager, Sennheiser Pro Labs, “we’ve seen a variety of microphone techniques. For crowd noise, we’ve seen a lot of benefit from using a dual-diaphragm mic, like the MKH 800 Twin, especially in these kinds of non-coincident microphone techniques. With the 8030, you can achieve that effect with a double-midside [configuration] that’s easily placed somewhere and is less complicated for cable running. Choosing [specific microphones and techniques] is really about application and the constraints of time and locations or other types of limitations that sports [productions] may face.”

Sennheiser also has a single-mic solution for immersive capture: the AMBEO VR ($1,499) with its four matched cardioid capsules in a tetrahedral arrangement. However, Glasscock considers a unit like the 8030 a keystone for the array of microphones already aboard most remote-production trucks.

“We see a lot of value in that,” he says, “because people aren’t going to want to buy a different mic array for each application. I think having this toolset of baseline, high-quality microphones and maybe a couple of specialty microphones able to be used in different arrangements makes sense for the immersive application as the way most people will go.”

A New Approach

Voyage Audio SpatialMic

Voyage Audio is the new kid on a small but growing block, and its SpatialMic has a kind of Millennial-esque flexibility: it’s designed to accommodate various output configurations — stereo, 5.1.4, 7.1, etc. — internally and to adjust to future ones, such as 4.0.4 (no LFE channel) via firmware updates.

“It’s kind of interesting with broadcast right now,” says Voyage Audio co-founder Steve Silva. “It isn’t full Atmos yet, but I think that’s the trajectory and the goal for everybody. There’s still plenty of 5.1 around sports, like the Olympics, so the goal is to expand on what’s being done today. The demand is for a tool to get to those formats quickly, easily, and out of the box, so to speak. The way our microphone does that is to output 5.1.2 or 5.1 or 7.1 now, with updates coming for different output options. We can do a firmware update and unlock multiple format options, based on customer demands.”

Voyage Audio is marketing the $3,000 microphone to A1s as well as to rental and network customers. Among them are two freelance A1s: Jason Blood for FOX Sports and Matt Coppedge for CBS Sports.

Coppedge deployed one for the 2023 NBA All-Star Game and the SEC football season and networked several, using Dante connectivity, for Super Bowl LVIII in Las Vegas. “The [microphone] integrates perfectly with Dante Controller,” he said in a Voyage Audio case study.

Notes Silva, “It’s an all-Dante-connected AoIP microphone, PoE-powered, single-wire connectivity, so it’s easy to implement. Everything’s in the microphone, one cable out. And that’s exactly what we’re seeing: broadcasters want to achieve those channel counts as efficiently as possible.”

One and Done

Audio-Technica BP3600 eight-channel microphone

Although Audio-Technica single-point and stereo microphones are routinely used to create surround and immersive soundscapes, the company has developed a fully discrete eight-channel microphone. After an eight-year technical gestation, the BP3600 has been deployed for Olympics and MotoGP broadcast coverage. The microphone costs more than $5,100, but A-T also makes it available through its professional-rental portal. The eight discrete hypercardioid capsules can be used in any configuration to produce other multichannel formats, from stereo to surround. Its plug-and-play nature is also calculated to allow broadcasters to deploy it for sports.

“People are looking for an easy-to-deploy solution to create that immersive sound bed, and this microphone does that,” Gary Dixon, director, broadcast business development, Audio-Technica, points out. “You can set it up in under five minutes: the [capsules] are already spaced; there’s no external processing. This mic is just naturally set up for 5.1.”

Beyond large-scale sports deployments, Dixon says, most interest in the BP3600 has come from the immersive-music sector, a still-small category but one being heavily emphasized by Dolby and Apple, with the mic used mainly to capture room ambience. However, sports applications abound, including as an overhead-capture solution and as a fan-POV sonic surrogate at field level.

“You can get the feeling of what it’s like to be a person standing on the sideline,” he says. “You hear the crowd overhead. You hear people around you and on the sides, maybe activities behind you, the game in front of you. It’s going to give you a representation of wherever you put it, which is I think the key.”

Immersive-audio capture is that starting point for the entire format. Putting the listener in the same space as the sound, says Dixon, “is the ultimate goal.”

The Promise of Immersive Wireless

The recently FCC-approved WMAS technology allows significantly denser multiplexing of audio channels onto a single wideband RF carrier, and Sennheiser’s new Spectera WMAS product is intended to make immersive-sound capture wireless. The format supports data and audio control in a single RF carrier for such parameters as volume, audio level and settings, RF health, and battery status and brings immersive capture to wireless operations.

“WMAS and Spectera allow complete synchronization of wireless devices,” Glasscock says, “and will allow the ability to use mic techniques that otherwise couldn’t or would not be recommended to be used over wireless, such as any of the techniques that depend on phase or the relationship of phase between multiple capsules. Spectera and WMAS allow [those] microphones to be phase-aligned. It will make it easier for mixers to do advanced techniques without having to worry about how to run the cables or how to distribute an array of microphones and make sure they’re phase-aligned. And WMAS, the underlying technology, allows that kind of phase alignment for the first time from a wireless microphone system.”