Alex Freke-Morin MSc Audio Production Third Year MSC Thesis School of Computing, Science and Engineering Level Ducking Practice to Produce Aesthetically Pleasing Audio for Television with Clear Dialogue Author: Alex Freke-Morin Supervisor: Dr Ben Shirley and Matteo Torcoli 2018 1 Alex Freke-Morin Contents 1: Abstract ............................................................................................................................................ 3 2: Acknowledgements .......................................................................................................................... 4 3: Introduction ...................................................................................................................................... 4 3.2: Outline ....................................................................................................................................... 4 4: Literature Review ............................................................................................................................. 5 4.1: Loudness, EBU R-128 and ITU BS.1770...................................................................................... 5 4.2: Speech Intelligibility ................................................................................................................... 6 4.2.2: Informational Masking ........................................................................................................ 6 4.2.3: Native and Non-Native Listeners ........................................................................................ 6 4.2.4: Dialogue Level Control ........................................................................................................ 7 4.2.5: TV Mix Preferences ............................................................................................................. 7 4.2.6: Level Difference Effect on Intelligibility .............................................................................. 8 4.3: Audio Broadcast Standards Comparison Chart ......................................................................... 9 5: Existing Mixing Practices ................................................................................................................ 10 5.2: Documentary Classes............................................................................................................... 10 5.2.2: Sampling Method .............................................................................................................. 11 5.3: Loudness Differences Analysis ................................................................................................. 14 5.3.2: Foreground to Background Level Difference .................................................................... 14 5.3.3: Background Before Duck by Ducking Depth ..................................................................... 15 5.3.4: Integrated Ducking Loudness Vs Foreground Loudness ................................................... 18 5.4: Time Constants ........................................................................................................................ 20 5.4.2: Commentary over Music Ducking Envelope ..................................................................... 20 5.4.3: Attack Time Vs Release Time ............................................................................................ 21 5.4.4: Attack and Release Time Modes ....................................................................................... 21 5.4.5: Music Envelope Approaches Rationale ............................................................................ 22 5.4.6: Hold and Ducking Threshold ............................................................................................. 23 5.4.7: Mid Scene Ducking Rationale ........................................................................................... 25 5.5: Median Ducking Behaviour ..................................................................................................... 26 5.6: Existing Common Practices Summary ..................................................................................... 30 6: Proposed Recommendations ......................................................................................................... 33 6.2: Time Constants ........................................................................................................................ 33 7: Experiment Method ....................................................................................................................... 34 2 Alex Freke-Morin 7.2: Experiment Content ................................................................................................................ 34 7.3: Test Method ............................................................................................................................ 34 8: Results ............................................................................................................................................ 37 9: Discussion ....................................................................................................................................... 43 9.2: Participant Variety ................................................................................................................... 43 9.3: Mix Tolerance .......................................................................................................................... 43 9.4: Level Difference ....................................................................................................................... 43 9.5: Comparison with Existing Standards and Practice .................................................................. 44 9.6: Influential Variables ................................................................................................................. 44 10: Conclusion .................................................................................................................................... 46 11: Future Works ................................................................................................................................ 47 12: References .................................................................................................................................... 48 13: Appendices ................................................................................................................................... 51 13.2: Appendix A: Full State of the Art European Broadcast Specifications .................................. 51 13.3: Appendix B: Momentary loudness VS Integrated Loudness ................................................. 54 13.4: Appendix C: Test Instructions ................................................................................................ 55 13.5: Appendix D: Project Plan ....................................................................................................... 57 1: Abstract In audio production, level ducking is the practice of attenuating the level of the bed (or background) signal when speech is present. This is done in order to ensure full speech intelligibility, while keeping the rest of the content (e.g. background music) enjoyable. Being an art in itself, level ducking is loosely defined by mixing handbooks and broadcaster recommendations. Often the only given suggestion is that speech must be "comprehensible and clear". This work sheds some light on level ducking by investigating detailed technical attributes, such as ducking depth (i.e. the loudness difference between speech and bed) as well as temporal characteristics. The first part of the work analyses TV documentaries broadcast in the UK, France, and Germany. An overview of the found common practices is given. In the second part, the results of a subjective test are presented, where 20 normal-hearing listeners rate the same pieces of content mixed with different ducking depths. Results show high variance across listeners, but low within them, confirming the importance of the personalisation offered by object-based audio (e.g. MPEG-H Audio) also for level ducking. Non-expert and expert listeners preferred different ducking depths with statistical significance. On average, non-expert listeners preferred 13 LU, while expert listeners preferred 10 LU. 3 Alex Freke-Morin 2: Acknowledgements With great thanks to: Ben Shirley, Christian Simon, Harald Fuchs, Matteo Torcoli, Mary Hatalski, and Jouni Paulus for their valuable assistance and input. Special thanks to all participants who took part in the experiment and in testing. 3: Introduction One of the most common complaints television viewers give to broadcasters are ultimately about level difference, most commonly that the background (also known as bed, comprising e.g. music and effects) drowns out the foreground which is normally comprised of speech (Armstrong, 2016). This is a complex issue, but it is perpetuated by the complete lack of consistency among broadcasters and within most broadcasters too. Level ducking is a common procedure where the background level is reduced to give way to the foreground level, increasing the foreground to background level difference. None of the broadcasters analysed in this thesis have any standard or recommendation for level difference or level ducking. This thesis sheds some light on what broadcasters are currently doing and which ducking parameters should be used as a benchmark. With a common standard, mixers would be working