Cobalt Digital COMPASS 9085 Loudness Processor - Manual (Page 96)

Appendix A
Measurement Techniques For Various Program Material Forms
A-4 9085 PRODUCT MANUAL 9085-OM (V4.3)
Importance of an Anchor Element
ATSC A/85 defines an anchor element as the aural element in material that
serves as the item within a group of sounds that assumes a dominant role and
is the “center of attention”. For example, in a piece containing relatively
constant dialog (such as a typical commercial), the mix and creative input
would typically position this dialog as the predominate or “anchor” element
in the mix (in terms of both relative level and channel placement). As such, all
other elements would normally have levels that proportionally track and stay
well below that of the anchor element. For example, in program material
consisting of dialog and background sounds or music, the anchor element
would be dialog with other sounds substantially lower in level.
Note that in a given piece, the anchor element can change assignment within
the course of the material (for example, at the end of a commercial where
score music or a jingle now may assume the role of creative dominance and
correspondingly become the anchor element).
Assumptions and Conditions For Meaningful LKFS Measurements
Again depending on the material form, meaningful LKFS measurement and
assessment can be very straightforward or, conversely, require some
techniques to help ensure a meaningful assessment is obtained. Very
straightforward assessments can be obtained when the following are present
and/or observed:
• Typical production aesthetics with typical post-production refinement
using moderate, controlled compression and aural content density.
• Consistent audio levels in center channel throughout the piece (e.g.,
dialog or music score).
• Dialog (or equivalent) serving as an anchor element.
• Material containing no excessive periods of unusual loudness or
silence.
• LKFS is intended as a long-term measurement. The shorter the
averaging period, the less representative an assessment is of a given
pice of ingest material. Where feasible, an observation should run the
entire length of the ingest material. If the material does not contain an
anchor element, the predominate element (e.g., featured music or
obvious effects) should serve as the anchor.
In these cases, the Audio LKFS Monitor function can be used with its default
settings.
Figure A-2 shows an example (using a target LKFS of -24.0) where these
assumptions can be followed, and an example where certain techniques
should be applied in order to obtain a meaningful LKFS assessment.