Loudness in Practice

Loudness differences between television channels and programs are a well known problem. During commercial breaks or when switching between channels, the perceived loudness often changes more than preferred. To investigate the point of view regarding this problem of the various parties involved, a symposium was organized in the Netherlands. The symposium led to the founding of the “Loudness Committee Dutch Broadcasting”. This workgroup will explore new solutions for the problem of annoying loudness differences. Part of their research is to study standards of loudness measurement. This part of the research is done during a graduation project at the Utrecht School of the Arts of which this thesis is the result.

This thesis examines the causes of loudness differences, various loudness measurement models, and the infrastructure of the broadcasting industry. The conclusions of the thesis can also be read as an advice to the Loudness Committee Dutch Broadcasting. Loudness differences cannot be solved easily nor completely. However, an improvement can be made. The key to this improvement is the new ITU-R recommendation for loudness measurement called Leq(RLB). The Leq(RLB) is a new standard for measuring loudness in broadcasting. Using the new standard with an additional threshold, so that it can prevent misjudgment of programs with more than average silence, will lead to a better result in the perception of the majority of the viewers. In addition to this new loudness prediction method, a loudness meter is proposed which can indicate loudness on the spot and give direct feedback to engineers. Since such a device is not (yet) part of the ITU-R recommendations, it is recommended in this thesis to use a RLB-weighted VU-RMS meter to display instantaneous loudness.

The measures proposed in this thesis will make it possible to control loudness throughout all phases of the production process. By doing so, it will not be necessary to control loudness by processing the finished product. This will lead to better results and less unwanted side effects.

This project’s result are now part of the recommendations of the Loudness Committee Dutch Broadcasting.

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