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Neural Keeps Watch on Levels

We at Journal Broadcast Group and KTNV television here in Las Vegas are truly excited about the upcoming switchover to DTV broadcasting. The mission for all 12 of our group stations has always been to bring unique and compelling content to audiences. We're particularly proud of our new state-of-the-art facility for delivering improved digital programming to our Las Vegas viewers.

There are always speed bumps with the transition to any new technology, and this has been particularly true in dealing with digital audio. Like most stations, we've been dealing with loudness issues and noticeable transition problems between 5.1 network programming and local stereo content.

Before we built our new facility, we did what many stations did by controlling our encoders and decoders with GPI contact closures. This helped with switching between network 5.1 audio and local two-channel audio, but it didn't really offer a smooth transition between the two formats, or maintain consistent sound levels. We had no real time loudness control on our network audio, so we simply set the local levels to match.

In our old analog broadcast plant, we used conventional audio processors and upconverted the HD broadcast. While this worked okay for stereo audio, it could not handle 5.1 audio or the enhanced dynamic range available with the digital format.

Our new facility is 100 percent HD and was designed to broadcast down-converted SD in parallel, while managing both stereo and 5.1 audio. Whether it's HD, SD, 5.1 or stereo, sound quality for our viewers is very important to us.

When listing the features we needed to solve our digital audio problems, I was pleased to discover Neural Audio's products specifically addressed issues that we were dealing with. In the end, we chose Neural's THX Surround MultiMerge+Neural Loudness Control (NLC). The combination of the software performance and the small size made this an easy decision.


NLC uses a perceptual loudness measurement to gauge the overall loudness of the broadcast. After evaluation, NLC varies audio path gain so that output stays within the targeted loudness level (the same as the dial norm setting). Since we're correcting all of our audio to match the dial norm metadata we encode for our viewers, they always have consistent audio without the "compressed" sound of the analog signal.

After NLC, the MultiMerge handles anything we throw at it: mono, stereo and discrete 5.1 audio mixes.

Installation was straightforward and the Neural staff was very helpful when we had questions. Each MultiMerge+NLC is placed in the signal path just after our master control emergency bypass switcher as primary and backup units. This is right before our Dolby AC3 encoder and Tandberg encoder. At the same time, our downmixed stereo output is converted to analog and feeds our stereo generators.

I really like the idea of being able to "create" a product that exactly fits the needs of our new facility when it comes to handling audio. Neural Audio's software-based approach will give me more flexibility in making future upgrades and that will really help with budgeting. As director of engineering for Journal Broadcast Group, I have recommended the Neural Audio approach to loudness and 5.1 solutions for the remaining 11 television stations in our group.

For additional information contact Neural Audio at 425-814-3200 or visit