Dolby E meets the audio demands of a new generation
One of my favorite topics to talk about in a television environment is the audio component. Ask any television engineer who has been in the business for any period of time and he or she will most likely tell you that audio is generally treated as an afterthought to the video. Even in movies, audio is generally done in a controlled environment post-scene- shooting or in a Foley stage.
Natural sound is a very hostile environment when it comes to producing television products. Have you ever noticed how in a street scene when people are talking the traffic noises are in the background? Does that happen in real life, or do you find your conversations interrupted by honking horns and diesel buses?
The fact is that we see in a very small arc but we hear from every direction. Sounds attract our attention and cause our heads to turn in the direction of the sound. Our senses are therefore coordinated and anything that causes us to perceive a disconnection between our senses would be disturbing and annoying. Aren't you uncomfortable if you hear a sound behind you but cannot turn your head to see what it is?
THE HOME CINEMA
In the early television or movie theater environment this was not a significant problem because of the technology involved. The TV screen or movie screen was essentially co-located with the sound-source speaker, so all sound was from the direction we were looking. In movie theaters, that started to change with the introduction of Surround Sound systems and Sensurround. The idea was to psycho-acoustically remove the space between where we were sitting in the theater and the projection screen, in essence bringing us into the movie and making us feel that we are actually at the location rather than in a chair in a theater. Television also started down this path in the 1980s with the introduction of BTSC stereo and Hi-Fi VCRs.
If you compare the two environments you find what I believe are some interesting challenges that are unique to each environment. During the 1970s and 1980s, remember that the movie theater industry had fallen on hard times. Ticket prices were perceived as too high and fewer people were going to the movies, opting instead to stay at home. So movies had to deliver some experience to the viewer that they could not get at home. For big-budget productions, we went to the Cinerama theater, where the screen was actually designed to wrap around your field of view. There was the aforementioned Sensurround that used low frequencies to shake the viewers and, of course, Surround Sound, which really pulled the viewer into the production. What all of this technology is essentially trying to do is to make the viewer more a part of the program by restoring the sensory coordination between sight, sound and touch. If you lived in California in 1974 and saw the movie "Earthquake" at the right theater, there were points in that movie where the audience was ready to bolt out the door because the sensation was that a real earthquake was happening. In a way, the movie theater had briefly brought the audience into the film.
So what has all of this to do with DTV? Well, the television industry and movie theater industries have been playing to the same audience since they began. In the early days of movies, the theater screen was essentially 4:3. Part of the design of television was to be able to show the audience a picture in their homes in a format with which they were comfortable. Well, then movies had color, and then TV had color. Movie screens were big and then TV got big. Movies got a wide aspect ratio and guess what, TV is now getting a wide aspect ratio.
In truth, home sound systems are further along in their development and acceptance in no small part due to the release of movies on DVD. It is therefore quite possible to replicate the theater sound experience at home including the Sensurround experience, assuming you don't live in an apartment or a trailer. Obviously you could replicate the experience in either of these environments but in the former you have neighbors who might object and in the latter you might actually shake your house off the jacks. Home viewers have had stereo TV and theater Surround Sound for years and have been enjoying it with videos they rent or buy. Terrestrial digital television, regardless of whether it is high-definition or standard-definition, has 5.1 Surround Sound as an integral component. Since we are competing for viewers with the aforementioned sources, as well as with satellite and digital cable, it is in our own best interest to make sure that we use this technology to make our viewer more participants in the program than just observers.
How do we do that? Well at the very minimum, we must be able to pass the 5.1-Surround Sound to our viewers. However, we also want to be able to contribute to this content in a way that is acoustically as nondisruptive as possible. Think about this: If you are broadcasting a program from the network and you need to do a voice-over, you want to be able to seamlessly fade down the Surround Sound, make the announcement and then restore the audio to full level. We do this all the time in a stereo environment. To work in the DTV world we will need to be able to process the 5.1 channel, mix in locally generated material and then encode the audio and video for broadcast.
This is where we look at Dolby E as the solution. If you just look at the 5.1 channels (six, really) of audio and think in terms of discrete wiring it becomes a frightening and expensive prospect. Dolby E was designed to carry the 5.1 channels on an AES audio pair. In reality it is designed to carry up to eight channels of digital audio, which can be real important if you happen to be in a market where you have multiple languages. The beauty of the system is that it works with any compliant AES device, such as most modern VCRs.
Now I know many of us had bad experiences with AES audio, especially in the editing environment. That problem quite frankly was the result of poor implementation and testing of AES compliance in the early adopter's equipment. If you think Dolby E is the way you should go but are wondering about equipment, check out the Dolby Web site, www.dolby.com. They have a page for the Dolby E partners that lists which companies are participating and what products are compliant. I would also encourage you to ask product manufacturers that you are considering that are not listed if they are Dolby E-compliant and if so, why aren't they listed.
Like I said, passing what is coming through and being able to seamlessly contribute to the feed is the absolute minimum. At Iowa Public TV, we also create a lot of local content. We have been acquiring and editing in high definition since 1998, but we have stuck pretty much to audio production in stereo. However, as the audience gains in sophistication and expectation, I believe we will have to seriously start looking at producing in multichannel audio as well. The audience will hear differences before they actually see them. Clicks and pops and hiss and audio distortions all are less tolerable than equal amounts of distortion to video. We think to ourselves however, yeah, but we're not clicking and popping, we're putting out a pretty good audio signal; and yes, we are. Does anybody remember when broadcast quality meant the pinnacle of quality? Now, the fact is that virtually all home consumer products outperform the broadcast standards. When we get calls now about audio and video quality, we're not being compared to the station down the street but to the satellite feed, digital cable or the DVD. If we're going to compete in this market, we have to produce compelling content and we have to do it in a technically proficient manner.
I can hear people saying, "'Technically proficient manner?' What does that mean? No one really tunes in to watch technology." Yes, there is the "wow" factor of a new and exciting technology breakthrough like color or stereo or Surround Sound, but that doesn't really sustain viewership. However, technology can really hurt viewership. And it doesn't have to be "bad" quality to be perceived as poor. As available technology improves, the expectation of the audience elevates. A station that is putting out the same product that they did 10 years ago may be losing audience because they don't sound or look as good as another source that is playing essentially the same programs but with better technology.
As an engineer who went through the conversion to stereo, I would implore anyone planning a facility for multichannel sound to include quality-control monitoring in your design. Now Dolby will tell you that you need to have a separate room with isolation so that you can position yourself at the acoustic focal point and make qualitative judgements on the mix. In a post house or at a sound-sweetening facility I would agree, but in the broadcast world, where broom closets become sound booths, I doubt that this is a practical solution. I would recommend instead a reasonably quiet location with a device like a Wohler E Mon-1 that provides level meters and a headphones outlet so that you can listen to the mix or to individual channels. I am not endorsing the E Mon-1 as the one and only product out there for this type of monitoring; it is just the one that I am most familiar with. The important part is to make sure that there is a QC point of verifying the audio. Whereas L and R reversal is annoying, low frequency EFX to center could actually do some damage to a lot of home systems.
What I am getting at here is that broadcast is in a position of converting to digital, and that is a given. Our audience is much more technologically savvy than they have ever been. Realize I am not talking about the people who have VCRs flashing 12:00. Quite frankly, they don't understand why DTV is even being pushed; their TV is working fine. The audience that we need to reach is the generation that uses a computer to do homework and does PowerPoint presentations for show-and-tell. These are the folks that aren't going to watch a television show but will experience a media presentation and the way they experience this is through sight and sound.
Future US's leading brands bring the most important, up-to-date information right to your inbox
Thank you for signing up to TV Tech. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.