The evolution of broadcast audio is entering an important new phase. As audiences have moved from standard definition to HD and UHD video, expectations for the accompanying audio experience have evolved as well. Immersive and object-based audio technologies are now enabling broadcasters and media organizations to create sound fields that are more dynamic, engaging and intricately connected to the visual experience.
This evolution is particularly evident in live sports. Rather than simply reproducing a conventional stereo or surround mix, immersive audio can place crowd reactions, commentary, ambience, and other sound elements within a three-dimensional sound field. The result can make audiences feel as though they are inside the stadium rather than simply watching it from home.
Technologies such as Dolby Atmos and MPEG-H Audio (Fraunhofer) are making this possible. But while immersive audio creates exciting new opportunities, it also introduces a fundamental challenge for broadcasters: the more sophisticated the audio becomes, the more sophisticated monitoring and quality control must become as well.
From Channels to Objects
Traditional channel-based audio is built around a defined speaker configuration. Audio is mixed and mastered for formats such as mono, stereo, 5.1 or 7.1, with the expectation that the receiving device will reproduce the appropriate channel configuration.
Object-based audio takes a fundamentally different approach.
Instead of tying every sound element to a fixed channel, an immersive mix can contain individual sound objects accompanied by metadata describing characteristics such as their position and movement within the sound field. A renderer at the receiving end can then use that information to adapt the mastered content to the listener’s available speaker configuration.
In principle, this means a single immersive master can serve a much wider range of listening environments without requiring separate mixes for every possible speaker configuration.
That flexibility is one of the great advantages of object-based audio. It is also one of its greatest challenges.
The audio itself is only part of the equation. Metadata becomes an integral component of the listening experience. If that metadata is incorrect, missing or corrupted somewhere in the signal chain, the listener may not experience what the content creator intended—even if the underlying audio is perfectly intact.
Complexity moves into the Signal Chain
Immersive audio introduces additional complexity across virtually every stage of the broadcast workflow: production, encoding, transmission, decoding and playback.
Technology developers have taken different approaches to addressing this complexity. Dolby, for example, has evolved its existing audio ecosystem to support immersive audio, including Dolby Digital Plus with Joint Object Coding (DD+ JOC) and Dolby AC-4, which provides native support for Dolby Atmos. Fraunhofer’s MPEG-H Audio technology takes a different approach, incorporating immersive audio information and associated metadata into an efficient audio channel-based transmission framework.
From a broadcaster’s perspective, however, the underlying technology differences don’t change the fundamental requirement: the entire chain has to work together.
Production workflows need to accommodate immersive audio. Encoders need to correctly generate the required audio and metadata. Distribution networks need to preserve the relevant information. Transcoders need to maintain the integrity of the signal. And receiving devices—from set-top boxes to televisions and other playback systems—must correctly decode and render the experience.
Reuse of existing transport infrastructure can minimize the disruption associated with introducing immersive formats, but it does not eliminate the need for additional monitoring. Metadata identifying and describing the immersive audio experience must successfully navigate the distribution chain alongside the audio itself.
This is where confidence monitoring becomes increasingly important.
Confidence Monitoring must Evolve
Audio monitoring has always presented unique challenges.
Even in conventional channel-based workflows, engineers need to detect issues such as unexpected channel swaps, incorrect audio on alternate-language tracks, phase problems that can create silent areas in the listening space, and inappropriate absolute or relative loudness levels.
With compressed and immersive audio, the monitoring challenge moves further upstream.
Before an audio signal is decoded, metadata must be correctly specified for the decoder and renderer. Incorrect metadata can produce an incorrect listening experience even when the encoded audio itself is technically present and intact.
Go one step further upstream to the encoding stage, and the metadata must be inserted correctly into the transport stream so that the intent of the content creator is preserved.
Then consider the possibility of transcoding somewhere along the distribution path. Every additional processing stage creates another opportunity for an unexpected deviation from the original master.
For broadcasters, this means monitoring can no longer be limited to asking a simple question: “Does the audio sound right?”
Engineers increasingly need to ask: Are the audio channels correct? Are the objects present? Are they behaving as intended? Is the metadata correct? Has anything changed during encoding or distribution? And, ultimately, is the listener receiving the experience that the content creator intended?
Seeing the sound
Object-based audio adds another dimension to monitoring because sound objects have characteristics that change over time.
An object may move through the sound field during a sporting event, for example, while associated metadata determines how that movement is rendered for the listener. Monitoring therefore needs to provide engineers with a way to visualize objects and their behavior—not simply listen to an aggregate audio output.
This visualization can make otherwise difficult-to-diagnose problems immediately apparent.
A metadata configuration error that might be difficult to identify by listening alone can become obvious when an object is displayed in an unexpected location. Similarly, unexpected object movement, missing objects or other anomalies can be identified before they reach the audience.
This represents an important evolution in the concept of confidence monitoring. Engineers are no longer monitoring only signals; they are monitoring the relationships between signals, metadata and rendering behavior.
Lessons from real-world deployment
At Wohler, we have seen this evolution firsthand through our work with both Dolby and Fraunhofer.
Wohler has a long-standing relationship with Dolby and has developed monitoring solutions for Dolby Digital Plus for many years. As Dolby Atmos became increasingly important in broadcast, particularly for major live sporting events, we had the opportunity to extend that experience into monitoring immersive audio.
We have also worked with Fraunhofer on monitoring solutions for MPEG-H Audio. MPEG-H has been deployed in markets including Brazil, providing an opportunity to support broadcasters delivering immersive audio to large audiences. Most notably, Wohler supplied MPEG-H monitoring solutions to support the recent global soccer tournament in Brazil.
These experiences reinforce an important point: immersive audio can deliver an extraordinary audience experience, but that experience depends on the integrity of the entire signal chain.
When everything works correctly, immersive audio can create a remarkably convincing sound field. In a live sporting event, crowd noise, commentary, and other elements can surround the listener and create the sensation of being inside the venue.
But a failure anywhere along the chain can compromise that experience. The audio may still be present, the video may still look perfect, and the broadcast may still appear technically healthy—yet the audience may not receive the intended immersive experience.
That is precisely why comprehensive monitoring matters.
Monitoring the last mile
As immersive audio becomes more widespread, monitoring also needs to extend to the point of consumption.
Historically, broadcasters have focused heavily on monitoring signals within the production and distribution infrastructure. But the final rendering stage can be just as important. The signal that leaves a broadcaster’s facility is not necessarily the experience that reaches the viewer.
Set-top boxes, and other consumer devices perform the final decoding and rendering. Monitoring the HDMI output from these devices can therefore provide an important perspective on the actual customer experience.
This concept of last-mile monitoring is becoming increasingly relevant as broadcast systems become more sophisticated.
Wohler’s iVAM2-CMD, for example, enables monitoring of HDMI output from set-top boxes and HDMI dongles, helping broadcasters assess the signal at the point where it reaches the consumer.
Wohler’s MAVRIC software-based monitoring application, fully integrated with our in-rack monitors, enables broadcasters to bring multiple monitoring points together under a single point of control and gain end-to-end visibility across the signal chain.
The future is end-to-end confidence
Immersive audio is not simply another audio format. It represents a fundamental change in how audio content is created, transported, and experienced.
As object-based technologies become more widely adopted, broadcasters will need monitoring solutions that reflect this new reality. Monitoring must encompass not only audio channels but also objects, metadata, encoding, decoding, rendering and the final consumer experience.
The objective is ultimately straightforward: preserve the creative intent from the production environment all the way to the listener.
Immersive audio is here to stay, and its adoption is likely to accelerate as audiences become accustomed to richer and more engaging listening experiences. For broadcasters, the opportunity is significant—but so is the responsibility to ensure that the promise of immersive audio survives the journey through the entire delivery chain.
The future of confidence monitoring is about confirming that the right signal, with the right metadata, the right objects and the right rendering behavior, reaches the audience as intended.