User`s manual

Dolby
®
Media Meter 2 User’s Manual 5
Chapter 3
Measuring Loudness
3.1 Measuring Equivalent Loudness
Differencesinaudiolevelsbetweenprogramsandchannelsorbetweenprogramsand
commercialsareamajorannoyancetoTVviewers.Whileobvioustotheviewer,these
loudnessdifferenceshaveprovendifficulttomeasurewithconventionalmethodsand
equipment.
Foryears,theaudioindustryhasquantifiedthelevelofitsprogrammingusingpeak
programmeters(PP
M)andvolumeunit(VU)meters.Itisimportanttonotethatbothwere
developedandareusedtoread signalvoltages,andthereforemakenoattempttomeasure
subjectiveloudness.Thus,severaldifferentvoices,adjustedinlevelsothattheyalldeflect
meterstothesamemark,maysou
ndsomewhatdifferentinleveltothelistenerathome.
Thisproblemisoftencompoundedbytherapidresponseofthemeter,whichrequiresall
operatorstoperformtheirownindividualvisualintegrationoraveragingofthemeter
movementitself.
Dolby
®
MediaMeter2featuresDialogueIntelligence
technology,adoptedfromthe
awardwinningDolbyDP600ProgramOptimizer,whichautomaticallydetectsandthen
measuresloudnessonlyduringthepresenceofspeechinanaudiotrack.Enabling
DialogueIntelligenceallowsthe operatortosimplyquantifyallthesectionsofthe program
thatonlycontaineddialogueandusetheendingmeasurementva
luefor analysisand/or
normalizationpurposes.This valueisalsocommonlyusedtosetthedialogue
normalizationparameterwithinDolbybitstreams.
DolbyMediaMeter2offersthreemeasurementalgorithmchoicesinthesettingswindow,
asshowninFigure 31:
•ITURBS.17702
•ITURBS.17701
•Leq(A)
Figure31
Figure 3-1 Measurement Algorithm Choices in the Settings Window
EBUR128measurements,includingintegratedloudness,shorttermloudness,and
loudnessrange,areavailablewhenITUBS.17702isselected.DialogueIntelligencecanbe
usedwitheitherITURBS.17701orLeq(A).
Youcan measuretheloudnessofDolbyDigital,DolbyDigitalPlus,DolbyTrueHD,
Dolby E,andPCMfiles.