Sound Delay When Using Assistive Devices with Your TV

by Neil Bauman, Ph.D.

A man asked,

All wireless sound systems I have tried to date have a slight delay that creates an echo effect with the TV speaker sound. Does the TV Sound Box have this problem?

Not according to my wife. She’s the one that uses the Sound Box in our house. (I use a loop system on my TV.) But this is because we have old tube type TVs, not new flat-screen TVs.

I think your problem is not in the devices you are trying to use, but in your TV itself.

Here’s what happens. Flat screen TVs take longer to “paint” the picture than to process the sound that goes with that picture. As a result, the TV manufacturers have built a delay into the audio circuit to keep both in sync.

However, some/many TV manufacturers did not build in the same delay on the signal going to the audio output jacks on their TVs. Thus, the sound from those jacks (and devices plugged into them such as the TV Sound Box, loop amplifiers, etc.) are out of sync with the sound from the TV’s speakers. (As you can appreciate, this is not the fault of the device, but the fault of the TV manufacturer.)

To their credit, some TVs have a feature in the menu to adjust the time delay for signals going to the audio output jacks. I’d check your TV and see if this is the case. If it has this feature, set the delay so that the sound from the assistive device you are using matches the sound reaching your ears from the TV’s speakers and you’ve solved the problem.

Now, to make things more complicated. For some reason you may find that there is a delay feature on your TV’s menu for the audio output jacks IF they are digital (Toslink or Coaxial), but not if they are analog (RCA). If your TV is like this, choose the digital audio output, but now you’ll need to get a digital to analog converter (DAC) to convert the signal back to analog.

And here it gets even more complicated. There are two versions of DACs and which one you get depends on your TV. If your TV puts out standard (PCM) stereo, then you can use a DAC such as this standard stereo DAC for $22.56.

However, if your TV outputs Dolby 5.1 surround sound, then you’ll need a more expensive DAC such as this Dolby digital converter for $56.32.

If your TV does not have a delay option in its menu, all is not lost. You can purchase a sound delay corrector (such as the Lip Sync Corrector) and put it between the audio output jacks on your TV and the device you are hooking up to those jacks. The sound delay corrector has a control on it to set the appropriate delay so you hear sounds via the TV’s speakers and your assistive device at exactly the same time.

You can get a Lip Sync Corrector for $78.71 or $84.15.

Note: these Lip Sync Correctors are analog devices—they use RCA jacks for both input and output. If your TV doesn’t have RCA output jacks, then you’ll have to get a Digital to Analog converter (DAC) as mentioned above, and a Toslink or coaxial cable to go from your TV to the DAC. You’ll also need a double male RCA patch cord to connect the output of the DAC to the sound delay corrector input, and an RCA to 1/8″ audio patch cord from there to the assistive device into which you are plugging it.

As you can see, depending on your TV, the solution can be relatively simple if your TV has the necessary features already built in, or it can get a bit complicated if your TV doesn’t have those features. But the good news is that, in any case, you can get around the problems one way or another and have the sound from your assistive devices in sync with the TV’s sound and picture.