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5 | Instruments | 5.7 | Dialnorm EN-56
Manual | TM3-3GS
The idea behind this scheme is that the perceived total loudness of a mixed
audio signal may be determined and kept constant at the listening end by
using the dialogue level (optimized for a combination of good intelligibility
and minimal nuisance through excessive volumes) with its fi xed loudness
ratio in relation to music and sound effects as a reference. ATSC standard
A/52 specifi es the transmission of the Dialnorm parameter as part of
the meta data. This Dialnorm value is determined by means of a method
normally used in noise pollution measurement, e. g. by measuring Leq(A),
the energy-equivalent A-weighted sound pressure level as defi ned in IEC
60804. Dialnorm makes use of this standard with the exception that it
measures the electrical signal level with reference to 0 dBFS instead of
using the sound pressure level with a value of 20 μPa as a reference. The
Dialnorm value with 0 dBFS as a reference corresponds to the measured
Leq(A) value. The concept uses a threshold value of –31 dBFS. In the
decoder, Dialnorm values above –31 dBFS lead to a level reduction of the
total audio signal by (31 dB + (Dialnorm)) [dB]. In TM3-3G the weighting
fi lter of the selected standard in the preset will be applied.
Dialnorm has no effect on the dynamics of the overall audio programme
or the loudness ratios of dialog, music, and effects. Only the overall level
of the programme is controlled in relation to a reference value. This ove-
rall level is reduced if the Dialnorm value exceeds this reference value.
To this end, the Dialnorm value is used by the decoder at the receiving
end to control the average overall volume in order to achieve a constant
perceived loudness. This correction operates very smoothly and will not
be noticed by the listener.
Factory presets using the Dialnorm instrument:
•
None