TV-BAY
Get Adobe Flash player
Having invested in a 3D or HD television, viewers not only expect the best possible picture, but also the best possible sound. In the past this was something that producers did not have to worry about as a majority of their audiences would be listening to content through paper speakers on the back of their CRT sets. But as sound systems have become more sophisticated, so has the viewers’ perception of broadcast sound. As such, producers need to ensure that levels are consistent throughout content and are not loud enough to cause distortion or quiet enough to be noisy. However, level metering is not ideal for measuring the actual perceived loudness, which depends upon the content and duration of sounds. This is now being recognised by broadcasters and international bodies, which have finally taken action, developing an accurate means of measuring perceived loudness, and drawing up specifications. Everyone is more or less agreed that ITU recommendations 1770 and 1771 are the world standard. In stereo, the phase of the output needs to be checked, which is even more important for surround sound. Substantial out of phase audio makes audiences feel uncomfortable at the best of times and physically sick at worst. Channel separation and balance also need to be monitored. So, as can be seen there is much to be tested if overall quality is to be assured, but what to test it on? Producers need to ensure that they meet several requirements if they are to offer a great return on investment. Accuracy undoubtedly needs to be a top priority. If T&M equipment is producing inaccurate results, then any changes that are made as a consequence are also likely to be wrong, and could make matters worse. those that can both generate the test signal as well as measure the results. Additionally, it needs the flexibility to be able to measure what is most appropriate for the particular application. While this sounds as though the equipment needs to be large and unwieldy to include these elements, T&M devices must be small enough to be able to be kept in production areas as well as be intuitive to use and produce results that do not need a specialist engineer to interpret. Finally, this should all be affordable for broadcasters and producers to check signals every time there is a process that could cause signal degradation. With all this in mind, producers need to consider if their existing test and measurement equipment meets the grade, needs to be calibrated, or if they need to get advice and revise their T&M requirements entirely. As we are talking about test AND measurement equipment, the most cost effective devices are BRADLEY TV-BAY MAGAZINE | 55 TV-BAY067JUL12.indd 55 05/07/2012 22:24