Next-Gen Audio Goals: Immersive, Personal

A next-generation TV standard demands a next-gen audio system, and that’s exactly what the Advanced Television Systems Committee has been focused on over the past two weeks as three competing recommendations have been submitted for consideration to be the ATSC 3.0 standard.

The systems — one each from Dolby Laboratories and DTS, and another from the triumvirate of Technicolor, Fraunhofer and Qualcomm — offer broadcasters the tools to continue delivering what viewers are accustomed to receiving today while positioning the industry to offer a much richer audio experience in the not-too-distant future.

While each has unique characteristics, all of them incorporate a new sound technology known as object-based audio that makes it possible for the systems to deliver two enhancements ATSC has stipulated for ATSC 3.0, says ATSC President Mark Richer.

First, next-gen TV audio must provide “personalization” of sound and “the ability to customize the audio program based on the viewer’s unique needs, environment or device,” he says.

Second, ATSC 3.0 audio must enhance “surround sound, bringing a much more enveloping experience to both the home theater and headphone listener,” he adds.

That enveloping sound experience is known as immersive audio, which entered the public arena in spring 2012 when Dolby Laboratories introduced Dolby Atmos for theaters.

Since then, some 200 films have been produced using the technology and more than 900 theaters worldwide have been equipped to play it back. In fall 2014, the Dolby technology became available for consumers in home theater systems, and last week the company recommended Dolby Atmos to ATSC for its next-gen TV standard.

“Immersive audio is really all about engaging our sensory system in a natural way,” says Jeffrey Riedmiller, senior director, sound group, Dolby Labs. 

Unlike today’s channel-based audio in which sound is assigned to come out of speakers at fixed locations, such as left, right and center, along a horizontal plane, object-based audio describes the essence and characteristics of a particular piece of audio content with metadata, says Michael Demeyer, Dolby Labs senior director, e-media.

“In the case of immersive audio, one of the common things that data describes is where in the room a sound comes from at a particular point in time,” he explains.

David McIntyre, VP corporate strategy and development at DTS, which has recommended its DTS:X immersive audio system for ATSC 3.0, compares this aspect of immersive audio to computer graphics. Rather than on-screen objects changing position along the X, Y and Z axes over time as they do in a 3D animation, sound changes its location in the room over time in an immersive audio environment, he says.

“This is somewhat simplified, but the metadata describes the position of a sound at a certain time and at a certain amplitude,” he explains. “Say I want the sound of a baseball being pitched. I want that audio to be an object that sounds as if it’s going from back to front directly through me.”

An immersive audio consumer decoder will know how many speakers are in use, their position and any special sound-focusing ability they may have to make the best possible effort to reproduce the zip of the baseball by projecting sound to the right location throughout the duration of the ball’s delivery.

“Speakers are like pixels,” he adds. “The more you have the finer the grain of the picture that can be painted.”

Object-based audio also makes it possible for individual viewers to personalize their experience with sound. “Imagine that the play-by-play broadcast announcers for a ballgame are put into audio objects,” says Alan Stein, Technicolor VP of technology.

“This makes it possible for individual viewers to control the volume of those objects [the commentators] independent of the volume of the crowd noise,” he says.

Technicolor, along with Fraunhofer and Qualcomm, have recommended MPEG-H Audio to ATSC for its new digital TV standard.

“The inability to effectively hear the storyline of a program or the sound of announcers over background effects, such as those at a sporting event, is a real problem for the current DTV audience,” says ATSC’s Richer.

Increasing the sound level of dialogue and decreasing that of music, effects and background noise may prove particularly helpful for those with hearing impairments as well as people listening to television on a future ATSC 3.0 mobile TV receiver, especially if they are in noisy restaurants or transit stations.

Other ways to personalize audio are also supported by an object-based audio system. For example, a descriptive soundtrack for those with visual impairments can be an audio object. A second-language track also can be an audio object.

“Today when you listen to primary audio during primetime you are likely to get 5.1,” says Dolby Labs’ Riedmiller. “But if you want to listen to that program in Spanish or French or whatever it might happen to be, typically you are only going to get stereo and maybe only mono [on the SAP channel].”

However, assigning an audio object to a legacy 5.1 surround mix in a second language is an easy way for broadcasters to deliver the same high quality of sound to both native and non-native speakers.

These sorts of benefits may make the rollout of ATSC 3.0’s audio component somewhat different than the introduction of 5.1 Surround Sound with HDTV, says Riedmiller.

As with the surround rollout, local stations are likely to confine their involvement with immersive at first to passing pass through network productions of special sports and entertainment programming.

However, unlike the 5.1 experience, local broadcasters have a reason to get involved with the personalization of sound from the start because doing so directly affects things like audio intelligibility and usefulness for viewers, he says.

Of course, all of the benefits of next-generation TV sound are contingent upon ATSC 3.0 becoming a real standard and then being authorized by the FCC and supported by the consumer electronics industry.

However, if ATSC 3.0 can surmount those hurdles, the recommended audio systems under consideration today promise to position the television industry to take on the future.

“Look at what you have to compete with today, and look at what’s going to happen in the next 20 years outside of broadcast or even within broadcast,” says DTS’s McIntyre.

“You need a system that can grow and adapt. The ATSC 3.0 system is going to have to have the ability to change, adapt and offer choice. And that’s exactly what’s being considered today.”

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