by Neil Bauman, Ph.D.
A lady explained,
My father is experiencing hearing loss and currently has an analog television. I’m trying to research what to look for in a new HDTV that would also allow us to hook it up to a room loop. (or is any TV on the market compatible to loop? are any better?) Can you help?
Sure I’d be glad to help you. Although you can connect any TV to a loop system—one way or another—when it comes to connecting loop systems to a TV, all TVs are definitely not equal. Some have features that make it easy to connect a loop system to them with minimal hassle. Others lack such features. As a result it can be more complicated (and expensive) than it need be.
Therefore, if you are shopping for a new TV to use with your loop system (or any other assistive device for that matter), try to find a TV with as many of the following features as you can. In addition to your personal preferences for size and other options, your ideal TV will have the following four features.
1. RCA (red and white) analog audio output jacks.
Almost all loop amplifiers require analog inputs. Thus the ideal TV would supply the standard red and white analog RCA audio outputs.
Unfortunately, many new TVs have dispensed with these RCA jacks and now only have coaxial (what looks like a single orange RCA jack) or TOSLink (optical—square black with a “trap door”) audio output jacks. In addition, some of these TVs only output 5.1 digital surround sound (Dolby) audio signals, whereas you want standard PCM output—just left and right stereo channels.
2. The audio output is fixed, not variable.
Only fixed audio output gives a constant loud signal going to the loop amplifier. If the output is variable, you never can mute the sound without turning off the sound to the loop. Nor can you turn down the sound below a certain point because, if you do, there isn’t enough signal getting to the loop amplifier to properly “drive” it. Thus the sound on the loop will be much too weak to hear properly.
3. The sound going to the speakers (variable) and the sound going to the audio output jacks (fixed) are mutually independent.
The audio output setting to the speakers (variable) should be separate from, and independent of, the audio output settings to the audio output jacks (fixed). This means you can set the TV’s menu such that you can vary the sound of the TV’s speakers (or completely mute them) while, at the same time, you still have a constant (fixed) audio signal going to the audio output jacks that are hooked to the loop system. As a result, you could listen to the TV at any volume you choose (or mute it) and it won’t affect the fixed level signal going to the loop amplifier. When you have this, the hearing person controls the volume of the TV at the speakers so it is not too loud for him, yet the hard-of-hearing person always hears beautiful clear sound via the loop system.
Some TVs let you set the audio output to either fixed or variable—but when you set the audio output to fixed, it mutes the sound to the TV’s speakers. This means the hearing people can’t hear the TV with the loop is on. Note: some TVs have three settings on the menu—“Internal”, “External” and “Both”. Typically, you’d want to set it to “Both”.
4. The TV has a menu setting to independently change the audio delay from between 0 ms (milliseconds) and about 250-300 ms for both the speakers and the audio output jacks.
This is necessary because in modern TVs, the processing time for the video signal is greater than it is for the audio signal. As a result, the TV’s built-in speakers incorporate a delay circuit to synchronize both signals so you both see and hear the audio and video at the same time. Unfortunately, this is seldom done with the audio outputs. Thus, you need a way to delay the audio signal so the audio you hear through the loop system via the TV’s audio output jacks is properly synchronized with the video. If this is not done, there is a definite “disconnect” that makes it hard to comprehend what is being said. In other words, what your eyes see (speechread) and what your ears hear need to occur at the same time.
Note: you may have to check the TV’s manual to find out whether the TV has this feature or not. So far, this feature has not been listed in the specifications for some reason.
Therefore, before you purchase a new TV, look for the above four features. Hopefully you can find a TV with all four of these features. If not, get the one that has the most of these features.
There are workarounds for each of these features if you cannot find a TV with all of them. Just be aware that each missing feature makes things more complicated (and expensive) to work around, but you can make them all work in the end if you persevere.
One more thing—make sure the TV your choose has good closed captions that are easily readable and adjustable as to size, color and placement, and easy to turn on and off. People with poor hearing need to be able to read the words as they are spoken in addition to hearing them.
Work Arounds for Missing Features
If you can’t find a TV with all 4 features mentioned above, here is how you can work around each of these problems.
1. If your TV doesn’t have RCA audio outputs, there are two ways to compensate for this.
If your TV doesn’t have any audio output jacks at all, you’ll need to get a microphone, attach it to the front of your TV’s speakers and plug the microphone into the loop amplifier’s microphone input jack. (This isn’t ideal as the microphone will also pick up some ambient room noise, but it is much better than nothing!)
If your TV doesn’t have RCA audio output jacks, but has coaxial or TOSLink audio output jacks, then all you need to do is get the appropriate digital to analog converter (DAC). Here’s where it gets a bit more complicated. You have to determine whether the TV puts out PCM (standard stereo) audio, or whether it put out Dolby 5.1 digital surround sound. Some TVs can output either—you select what you want in the TV’s menu options.
If you have PCM (stereo) outputs then you can use this or a similar DAC. However, if the TV only puts out Dolby sound, then you need a more expensive DAC that specifically handles 5.1 Dolby output such as this DAC. (If you don’t know what kind of audio your TV puts out, get the more expensive Dolby 5.1 DAC as it automatically handles both PCM and Dolby signals.)
There is yet another complicating fact of which you need to be aware. Some TVs automatically change the output between PCM and Dolby depending whether the input signal is analog (NTSC) or digital (ATSC). In this case, just use the DAC that can handle both the analog and Dolby sound (the more expensive one) and all should be well.
2. If your TV only outputs variable audio, you need to get the audio signal from a “box” connected ahead of the TV, not from the TV itself. This “box” could be your cable box, set-top box, satellite box or even a DVD or VCR recorder-player. All that matters is that this “box” is hooked up in series to the cable ahead of the TV in question.
Often one of these “boxes” will have the requisite RCA jacks, or at least a coaxial or TOSLink jack. If the latter case, you’d need to also use the appropriate DAC. (If your TV takes the signal straight from an antenna or a cable jack in the wall, then you can’t use this method. Basically, you’re out of luck, unless you purchase a DVD or VCR recorder/player and hook it up ahead of the TV.)
Note: when you take the audio signal from another device with a TV turner built in, you have to make sure you have your device and the TV set on the same channel, or else you’d be hearing the audio from whatever channel the other device is tuned to and seeing the video from the channel your TV is tuned to (unless you wanted to listen to the game on one channel, while at the same time watch a different game on another channel).
3. If your TV turns off the speakers in order to give fixed audio outputs, then you either have to follow the procedures in step 2 above, or, if the hard-of-hearing person is the only person that watches the TV, just leave it set on fixed audio out and listen via the loop system. One advantage of doing this is that you can guarantee the TV won’t disturb anyone else.
4. If your TV does not have a built-in delay for the sound signal at the audio output jacks, you can get a Lip-Sync Corrector for about $79.00 and connect it between the TV’s audio output and the loop amplifier’s input. Then you adjust the delay so the sounds and video are synchronized properly.
Note 1: The Lip-Sync Corrector is analog (has RCA jacks) so if your TV has RCA audio outputs, you just connect it between the TV and loop amplifier. However, if your TV has digital audio outputs, you need to use a DAC as well. Connect the DAC to your TV’s digital audio outputs, and then connect the Lip-Sync Connector between the analog side of the DAC and the loop amplifier.
Note 2: If you are using a cable box, set-top box, etc so you are not getting the feed from the TV itself, then having the delay built into the TV won’t help. The delay needs to be built into the “box” from which you are getting the audio feed. If that device doesn’t have a built-in delay that you can adjust, you will also need the Lip-Sync Corrector so you can adjust the delay to synchronize the video and sound between your TV and loop system.
I hope I haven’t snowed you under. If you get a TV that has all four of the above features, it should be very easy to set up a room loop system. (Remember, the above applies to any other assistive devices that you might hook up to your TV as well. These problems are not unique to loop systems.)