April 2020

Immersive: The New Gold Standard Of Sound
The sonic search is an exciting journey!
Article By Dennis Baxter

  The evolution of audio in broadcasting and film has paralleled the increase in the number of audio record and transmit channels available in the ecosystem. Analog satellite technology provided two channels of audio and often one channel was for a full program and one channel for the program without commentary – hence mono audio except for special events.

Through the early 1980s, stereo was often electronically processed from mono and original surround sound was processing from two channels to create five channels of sound. Supposedly, the unprocessed channels were what one of my NBC friends called enhanced stereo and if you decoded the two channels you would get surround sound. Well, not only did the stereo sound awful, but the surround was just as bad. Compassionately, one must remember this was a transition period for enhanced sound.

Two-channel sound over an analog transmission path was not going to improve until there were more channels. Analog sound had limited expansion possibilities, but digitization brought new technology that accelerated the development.

Digital HD service brought discrete surround sound. It became common for broadcasters to transmit discrete 5.1 Surround Sound directly to the consumer and let the home set-top box decode the digital signals as needed – stereo or surround sound. UHD and new television standards gave audio a purpose and new possibilities with the promises of a considerable increase in the channel count - up to 16 channels. This has resulted not only in immersive, but also interactive sound over a very limited bandwidth.

Audio reproduction has developed and evolved from a single dimension sonic space to a fully immersive, multi-dimensional soundfield. Dimensional sound is the next phase in creating a true gold standard sound experience. The use of height speakers is subjective and clearly dependent on the content, but one thing is clear: height speakers give greater resolution and creative possibilities in audio reproduction.

Stereo and surround sound reproduce audio only in the horizontal plane – in front, to the sides, and behind the listener. Immersive sound attempts to put the listener in a complete sound space with sound around the listener from every direction. Immersive sound finally gives the third dimension.

What Is Immersive Sound?
As you move from a single point mono reproduction of sound to two channels / speakers and more, the listener perceives a greater illusion of dimension. As a general postulate, as the number of speakers increases the sense of realism increases as well. Consider it this way: mono sound is one speaker and binaural and stereo sound are two speakers. Speaker based 5.1 surround is one for one channel to speaker or six total and Immersive Sound begins at 5.1.2 or eight channels and has working configurations up to 22.2 or twenty-four channels and speakers. 7.1.4 is twelve channels and twelve speakers and a format that seems to be where the film industry resides. The speaker configuration for 7.1.4 includes two middle speakers and four height speakers. Sports generally do not use the middle speakers and I have heard some discussion from broadcasters about having only two front height speakers which would be 5.1.2.

The verdict is out as to what immersive sound for television means because, while most global broadcasters seem to be settling in on 5.1.4 or 10 channels, the Japanese are still pushing 22.2. News flash... the Japanese National Broadcaster will produce the 2020 Summer Olympics in 8K picture and 22.2 sound. I have asked privately how large an audience does NHK expects to draw – so far no official response.

In addition to speaker-based reproduction, there is ambisonic and object-based audio as well. Speaker-based audio is where the sound is mixed and reproduced over the same speaker configuration. This is probably what you have in your 5.1 surround sound home theatre system. One fault of surround sound was that it was intended to be reproduced in the same six-speaker setup and mixed.

Object-based sound is an interesting concept because separate channel elements are delivered to the listener separate of the base or foundation mix. For example, film immersive is 7.1.4 which is twelve channels. That leaves four channels for different languages or special effects. These object channels can be placed anywhere in the soundfield with an accompanying ambiance.

I found that Ambisonic sound reproduction reproduces a more spatial feel because it spatializes the entire soundfield differently, giving a superior sense of depth.

The Beauty Of The Future
Whether you are listening over headphones, stereo, discrete 5.1.2, 7.1.4 or 22.2, soundbars, Ambisonics, object or speaker-based audio production, the beauty of the future is the ability to render perfect audio for the listeners. The listener can tell the decoding processor what their listening configuration or preferences are, but ultimately, there will be an intelligent interface that senses the incoming data. Content for home reproduction broadcast and broadband reproduction -vs- theatre-based reproduction is ultimately mixed differently and separately to compensate for the differences in speaker reproduction.

Several distinctly different content genres benefit from immersive sound production which can result in varying interpretations of what immersive sound is. Fundamentally these are post-produced programming and there is live content such as entertainment and sports - each variety of content benefits differently from immersive sound production. There is no doubt that post-produced content like movies and made-for-TV programming benefits from immersive sound production. For example, when there is an airplane or a weather incident there is a reason to have sound above the listener/viewer. With live sports and entertainment productions, the sound simply benefits because the listener can simply enjoy an enhanced spatial experience far beyond any horizontal speaker reproduction like 5.1 surround.

Music is coming into the immersive sound arena and I have found that separation and spatialization are powerful creative and production tools for music. Remember when you first realized the left and right visual imaging and panning of the drums matched in that music video? Now take the tom-toms and cymbals and elevate them above ear level or put the tweeter of a rotating Leslie Speaker Cabinet above the listener and spatially pan the low bass rotating speaker around the listener at ear level.

Immersive sound offers dimensional reality, spatial enhancements, sonic unmasking, and artistic creativity – plus more. If you are considering upgrading to an immersive sound system there are a few things to consider beyond the artistic content you enjoy. The major question with spatial sound reproduction is the choice of speaker reproduction. There are only two choices – discrete speakers or soundbar-type arrays or perhaps a hybrid. I understand that discrete speaker reproduction tends to be the preference of the audiophile and twelve speakers in the home theatre are very acceptable, but not so much in the kitchen or bathroom.

Pure discrete immersive sound can be accomplished with speakers mounted above and pointing down at the listener or by simply placing up-firing speakers on top of floor speakers. Ceiling mounted speakers are not dependent on reflecting the sound off a surface like the ceiling and walls like an up-firing speaker. Direct sound will probably be more accurate in localization; however, I have heard some very convincing soundbar systems that are completely dependent on reflected sound for the immersion illusion. Ceiling mounted speakers require wire and power and are a challenge to install. Frankly, installation may be a factor in your immersive speaker decision.

The final component of the Next Gen data stream is interactivity. The television experience has been essentially a passive one. Digital distribution has made possible basic interaction for purchasing pay-per-view content, but true interactivity gives the consumer entertainment options and content creators creative and monetary options. For example, you often see the coaches pacing back and forth screaming at the players - but you rarely hear it.

Next-Gen Audio gives the consumer all levels of auditory experience plus additional audio channels to supplement the experience. If the consumer is willing to accept unfiltered language, they could tune into their coach's audio which is not part of the broadcast mix. The consumer could have access to racing radios, microphone on athletes, different commentary for home and away teams – the list goes on. User control has always had its fascination with the audio curious. I remember the first amplifier I had that had the loudness control – bass boost.

The sonic search is an exciting journey! I can not hear the difference between gold plated wire and connectors and copper ones, but I guarantee you will immediately hear the difference when you add height speakers. It's unmistakably the new gold standard in sound.

Biography
Dennis Baxter has spent over 30 years as a sound designer contributing to hundreds of live events including 9 Olympics Games. He is the author of A Practical Guide to Television Sound Engineering, published in both English and Chinese and is currently working on a book about immersive sound practices and production. He can be reached at dbaxter@dennisbaxtersound.com.