Revised Low Frequency B Curve (Soulodre)


The revised low-frequency B-weighting (RLB) analyser implements a method of sound level measurement designed for the monitoring of broadcast audio level. RLB is similar to B-weighting, except that the high frequency transfer function is flat (instead of having a high frequency roll-off). This spectral weighting was found to be an effective objective measurement of loudness of typical broadcast material by Soulodre (2004), and is recommended for use by the International Telecommunication Union. Soulodre and Lavoie (2006) found that this spectral weighting could be used for a short term loudness meter with a running rectangular integrator of between 1 s (too short) and 10 s (too long). An integration time of 3 s was chosen as a compromise. This analyser implements these concepts.

User Controls

Integration times of 1 s, 3 s and 10 s can be chosen.


The output(s) are time series for each integration time selected.


G. A. Soulodre (2004) “Evaluation of objective loudness meters,” 116th Audio Engineering Society Convention, Berlin.
G. A. Soulodre and M. C. Lavoie (2006) “Development and evaluation of short-term loudness meters,” 121st Audio Engineering Society Convention, San Francisco.

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