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Ask the experts NUGEN Audio VisLM-H Loudness Meter displaying standard loudness parameters. with Jon Schorah, Creative Director, NUGEN Audio Loudness Q&A Loudness level inconsistencies are one of the most common problems in the broadcast industry. Loudness standards are now being introduced as discontinuities in audio levels between programs, or between programs and advertisements, have been the cause of viewer complaints – in fact they are the number one cause. Of course anything that causes complaints is a concern to broadcasters – complaints mean dissatisfied customers, reduced revenue from subscriptions and lowered ads, and now with the introduction of legislation, fines. Why should I care about the new loudness standards? L oudness issues are not only limited to how loud a program is. A common issue concerns indistinct dialog, which makes it difficult to hear a program’s presenter or actors over the background soundtrack and music. In a recent example of this, a flagship popular science series on a major British TV channel was the subject of hundreds of complaints as viewers struggled to hear the presenter over an intrusive musical soundtrack. The audio for programs like this is mixed on high-quality studio systems and what sounds good to the engineer, may be very different on the low-fi sound reproduction from most TVs. Another issue is audio quality, and the hyper-compression that crushes the dynamic range of the original audio source. Hyper-compressed audio sounds relentlessly loud and is very intrusive. The new standards remove the loudness advantage achieved with over compression and so a more dynamic mix becomes a viable, or even desirable alternative. And finally everyone in broadcasting should care about the new standards, because in many countries they are now enshrined in the law and you’ll be risking fines if you don’t meet them. But to put it at its simplest, better audio means happier viewers, as a recent example proves. An Italian broadcaster which was an early adopter of loudness technology found that its channels were quieter as a result, but its audience figures started rising because channel-hopping viewers noticed how harsh and noisy other channels sounded. How widespread are the standards? Standards are global, Asia and Africa excepted. Various names are used around the world for the standards but they are all essentially the same and are based on ITU-R B.S. 1770. There are some slight differences in interpretation but this doesn’t result in any notable difference in what the consumer perceives. In the USA the main measurement is called LKFS and in Europe it’s referred to as LUFS, but it’s essentially the same thing. There are lots of different loudness readings. What are they all for and which one should I measure? The main reading is integrated (or program) loudness – the overall average loudness of the content. Some standards aim for -24 LKFS, and for others it’s -23 (the European LUFS measure usually). Beyond this there are quite a few more detailed measures including the short term loudness reading, which measures loudness over the past 3 seconds. Some broadcasters specify a value for this to meet targets for maximum short term loudness values. There is also the momentary loudness reading, which measures over a 0.4 second window. This value varies a lot during the course of a program and measuring it is a way of making sure no sudden peaks occur. Another value, True Peak Level, is not strictly a loudness measure at all but a measurement of the inter-sample peak. Maximum peak measurement is specified in order to avoid noticeable clipping and distortion, but because of the way audio 46 | TV-BAY MAGAZINE TV-BAY067JUL12.indd 46 05/07/2012 22:24