To facilitate better consistency between programs and stations, ITU, EBU and ARIB have investigat... more To facilitate better consistency between programs and stations, ITU, EBU and ARIB have investigated the standardization of broadcast loudness. This paper examines some consequences of a global loudness standard with regard to metering and control at the Ingest, Production and Transmission stages. Findings are reported from the latest research into mono, stereo and multichannel loudness measurement of real-world broadcast sounds. The improvements achieved by the new loudness models are quantified against previous level descriptors, such as, for example, PPM and Leq(A). Besides from reducing consumer annoyance with jumping levels, less engineering time needs being spent per audio stream. This too, is important because digital broadcast means a significant proliferation of the number of channels and the number of platforms. Each platform, such as TV, radio, internet, podcast, and other personal entertainment systems, has its own requirements for dynamic range, frequency range and speec...
International broadcast is moving towards loudness based normalization. The paper reports how lou... more International broadcast is moving towards loudness based normalization. The paper reports how loudness based guidelines are being adopted in the US, Japan and Europe; and it details new tools to improve on ITU-R BS.1770, specified in a remarkable and concerted effort between broadcasters and researchers around the world. With the CALM act now passed by the Senate and by the Congress, transparent and predictable normalization of interstitials has become even more essential to production companies and to broadcasters. The good news is how recent additions to BS.1770 enable improved leveling of commercials and promos without sacrificing the possibility for broadcasting wide loudness range content such as film, drama and music. The paper describes how to root production, transmission and logging in a revised set of rules that may be used to create tighter delivery specifications than expressed in the first version of the ATSC A/85 recommended practices. Furthermore, the updated techniqu...
In-room estimates of loudspeaker responses at the listening location are typically taken either a... more In-room estimates of loudspeaker responses at the listening location are typically taken either at one microphone location, replacing the listener with a microphone, or averaging in space, at multiple microphone locations at and relatively close to the listening location. In-frequency averaging can attenuate the locality of the frequency response features in mid and high frequencies. In-space averaging extracts the common frequency response features visible in all the measurement positions. Spatial weighting combined with frequency domain averaging can increase the stability of the frequency response estimate for the features relevant for the subjective compensation of the sound color at the listening location. Spacing out the spatial average measurement points affects the nature of the spatial average and the focus on the frequency response features common to the measurement points. The spatial averaging points used in taking a measurement should be chosen based on the intention of...
To fully exploit new Reverb and Spatial algorithms for 5.1 and 7.1 environments in music and film... more To fully exploit new Reverb and Spatial algorithms for 5.1 and 7.1 environments in music and film, effect mixing procedures may have to be changed slightly. The paper will describe production techniques for positioning of sources and listener in virtual rooms, and an algorithm structure to achieve this.
Previously we introduced the concept of loudness descriptors-key numbers to summarize loudness pr... more Previously we introduced the concept of loudness descriptors-key numbers to summarize loudness properties of a broadcast programme or music track. This paper presents the descriptors: Foreground Loudness, which measures the level of foreground sound, and Loudness Range, which quantifies the variation in loudness. Wide loudness-range material may benefit from level-alignment based on foreground loudness rather than overall loudness. We propose to use these descriptors for loudness profiling and alignment, especially when live, raw, and film material is combined with other broadcast programs, thereby minimizing level-jumps and also applying appropriate dynamicsprocessing. Finally, we introduce the "zap test" which can objectively characterize the quality of loudness-balancing schemes, based on statistics of the potential loudness-jumps. A study of loudness-jump tolerance is presented, considering loudness-jumps from a subjective point of view.
This paper extends a previously published study of the differences between level normalization of... more This paper extends a previously published study of the differences between level normalization of programs using the two dominant methods: Loudness normalization and speech ("dialog") normalization. Instead of adding to the continuing debate of the subjective merits of one method over the other, important technical aspects are examined empirically. The difference in normalization level between Loudness and speech measures was up to 14 dB. For all films, the Loudness method provided the greatest headroom. Half the films could be broadcast at a fixed target level of −24 LKFS (loudness, K-weighted, relative to full scale) without dynamics processing. When it was speech normalized, not a single film could be broadcast at the same target level without applying dynamics processing. The study furthermore found a systematic difference between manual speech measurement and automatic speech measurement. The measured movies were also compared to the 2013 season of a high profile TV drama production. The loudness properties of the drama were found to be comparable to the movies. In addition, different broadcast/playback paths were found to have markedly different effects on the Loudness Range of the drama series. Uncertainties in classification, definition, and measurement are summarized and compared to the requirements for precision in Advanced Television Systems Committee (ATSC) and the European Broadcasting Union (EBU) loudness-based standards. Finally, consequences of these findings are discussed relative to ITU-R BS.1864, the International Telecommunication Union's standard on broadcast program exchange.
We present an empirical study of the differences between level-normalization of feature films usi... more We present an empirical study of the differences between level-normalization of feature films using the two dominant methods: loudness normalization and speech ("dialog") normalization. The sound of 35 recent 'blockbuster' DVDs were analyzed using both methods. The difference in normalization level was up to 14 dB, on average 5.5 dB. For all films the loudness method provided the lowest normalization level and hence the greatest headroom. Comparison of automatic speech measurement to manual measurement of dialog anchors shows a typical difference of 4.5 dB, with the automatic measurement producing the highest level. Employing the speech-classifier to process rather than measure the films, a listening test suggested that the automatic measure is positively biased because it sometimes fails to distinguish between "normal speech" and speech combined with "action" sounds. Finally, the DialNorm values encoded in the AC-3 streams on DVDs were compared to both the automatically and the manually measured speech levels, and found to match neither one well. 1 L eq = equivalent continuous sound level
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Papers by Thomas Lund