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Evaluation of the Momentary Time Scale for Live Loudness Metering

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Different ballistic definitions for the momentary time scale used in live loudness measurement were evaluated. Definitions from the ITU and EBU were compared as well as a faster version of the ITU version, two asymmetric time scales and the deprecated ballistics, defined in EBU Tech 3205-E, for peak program meters. The goal was to identify the ballistics definition that would function as the best complementary tool to a short-term time scale. Engineers within the broadcast industry and students in audio technology performed an audio alignment task in a simulated live broadcast environment using one ballistics definition per trial. Fader movements and output levels were recorded. After each trial, a set of assessment scales were rated by the subjects. Some results were: a decay time constant of 250 ms yielded better representation of the low-level parts of the dynamics in the signal compared to a 400-ms time constant; the present ITU version of the momentary time scale yielded an estimated less eye fatigue; effects on the resulting output levels, related the gate in ITU-R BS.1770 in conjunction with live compensation of unadjusted audio material were shown.

JAES Volume 68 Issue 3 pp. 193-222; March 2020
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