TC Electronic LM2 Plug-in - Manual (Page 6)

6 / LM6 Radar Loudness Meter
Introduction
Since 1998, TC has performed listening tests and evaluation of loudness models;
and therefore holds an extensive, Universal Database of loudness, based on ten
thousands of assessments. The database covers all sorts of broadcast material,
music, commercials, feature film and experimental sounds, and is verified against
other independent studies.
Fig 1.
Left: DRT for consumers under different listening situations
Right: Peak level normalization means that material targeted low dynamic range
platforms gets loud.
The Universal Database is authoritative from an academic as well as a practical
point of view. It has been indispensable when designing the LM6 meter, because it
provided the missing link between short-term and long-term loudness, and enabled
the statistically founded Universal Descriptors of LM6 .
The chart of Dynamic Range Tolerance in Fig 1 is a side-effect of the studies
mentioned: Consumers were found to have a distinct Dynamic Range Tolerance
(DRT) specific to their listening environment. The DRT is defined as a Preferred
Average window with a certain peak level Headroom above it. The average sound
pressure level, which obviously is different from one listening condition to another,
has to be kept within certain boundaries in order to maintain speech intelligibility, and
to avoid music or effects from getting annoyingly loud or soft.
Audio engineers instinctively target a certain DRT profile when mixing, but because
level normalization in broadcast and music production is based on peak level