Level-Normalization of Feature Films Using Loudness vs Speech
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. AES 135th Convention Best Peer-Reviewed Paper Award Cowinner
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