LMn Manual
Table Of Contents
Interface and feature reference
LM2n / LM6n Manual 20
Max Momentary (M) descriptor
Max Momentary is the maximum momentary
value through the entire program. This is the
same descriptor that is also displayed by the
Outer ring of the Radar display in LM2n and
LM6n (see “Radar page” on page 17.
While Program Loudness concerns the entire,
full-length program, Momentary loudness is
measured in a window of 400 ms.
Max Short Term (S) descriptor
Max Short Term is the maximum momentary val-
ue through the entire program. This is the same
descriptor that is also displayed by the Radar
display in LM2n and LM6n (see “Radar page” on
page 17.
While Program Loudness concerns the entire,
full-length program, Max Short Term is mea-
sured in a window of 3 seconds.
Max True Peak (TP) descriptor
Max True-peak is the maximum true-peak value
seen over the entire program.
Peak/Loudness Ratio
(PLR) descriptor
Peak/Loudness Ratio is the distance between
Program Loudness (see “Prog. Loudness (I) de-
scriptor” on page 18) and Max True-Peak (see
“Max True Peak (TP) descriptor” on page 20).
Loudness Range (LRA) quantifies loudness vari-
ations inside a program or a music track. But
LRA isn’t very sensitive to transient-limiting and
clipping happening as a result of the loudness
war in commercials and music production.
Peak to Loudness Ratio (PLR) is a more appro-
priate measure of such squashing, which has an
adverse effect on clarity, intelligibility and audio
quality at large. In addition to its “educational”
value, PLR is also relevant when tailoring a track
or a program to a certain amount of downstream
headroom. For instance, ATSC A/85 and EBU
R128 provide 23 dB of headroom, while Sound
Check in iTunes offers 16dB of headroom.
Lowering PLR further only destroys audio quality
without gaining loudness on any modern plat-
form. Accordingly, keeping an eye on this crucial
reading can save your next recording for genera-
tions to come.