TC Electronic DB6, User Manual

Page: 152 / 174

LM6
DB6 English Manual (2014-10-07) 149
LM6 – Stat(istic)s page
The Statistics page gives an overview of essen-
tial descriptors:
►
Program Loudness
► Loudness Max
►
Loudness Range
►
True-Peak Max
► Sliding Loudness
►
PLR (Peak to Loudness Ratio)
About PLR (Peak to Loudness Ratio)
PLR (Peak to Loudness Ratio) measurements
often correlate with audio quality – be careful
not to force it too low. Programs and tracks
should be allowed to live.
! Important: Clicking the Reset button will reset
the meters and the log file.
Level versus loudness
When level normalization in audio distribution is
based on a peak level measure, it favors low dy-
namic range signatures as shown in Fig 1. This is
what has happened to CD.
Quasi-peak level meters have this effect. They
tell little about loudness and also require a head-
room in order to stay clear of distortion. Using
IEC 268-18 meters, the required headroom is
typically 8-9 dB.
Sample-based meters are also widely used, but
tell even less about loudness. Max sample de-
tection is the general rule in digital mixers and
DAWs. The side effect of using such a simplistic
measure has become clear over the last decade,
and CD music production stands as a monu-
ment over its deficiency. In numerous TC papers,
it has been demonstrated how sample-based
peak meters require a headroom of at least 3 dB
in order to prevent distortion and listener fatigue.
The only type of standard level instrument that
does not display some sort of peak level is the
VU meter. Although it has been developed for
another era, this kind of meter is arguably bet-
ter at presenting an audio segment’s center of
gravity.
However, a VU meter is not perceptually opti-
mized, or ideal for looking at audio with markedly
different dynamic range signatures.
Unlike electrical level, loudness is subjective,
and listeners weigh its most important aspects
(SPL, frequency contents and duration) different-
ly. In search of an “objective” loudness measure,
a certain
Between Listener Variability (BLV)
and Within Listener Variability (WLV) must be
accepted – meaning that even loudness assess-
ments by the same person are only consistent to
some extent, and depend on the time of day, the
listener’s mood etc. BLV adds ambiguity as cul-
ture, age and other parameters are introduced
as variables.
Because of the variations, a generic loudness
measure is only meaningful when it is based on
large subjective reference tests and solid statis-
tics. Together with McGill University in Montreal,
TC Electronic has undertaken extensive loud-
ness model investigation and evaluation.
The results denounce a couple of Leq measures,
namely A and M weighted, as generic loudness
measures. In fact, a quasi-peak meter showed
better judgement of loudness than Leq(A) or
Leq(M). Even when used just for speech, Leq(A)
is a poor choice, and it performs worse on music
and effects.
An appropriate choice for a low complexity, ge-
neric measurement algorithm, which works for
listening levels used domestically, has been
known as Leq(RLB).
Combined loudness and peak level meters exist
already, for instance the ones from Dorroughs,
but BS.1770 now offers a standardized way of
measuring these parameters.
In 2006, ITU-R Working Party 6J drafted a new
loudness and peak level measure, BS.1770, and