GettingStartedwithSmaart®v7:BasicSetupandMeasurementThisguideisanintroductiontothebasicmeasurementandoperationalconceptsembodiedinRationalAcoustics’Smaart®v7.Whileinnowayanexhaustivestudy,thisdocumentservesasastartingpointforuserstofamiliarizethemselveswiththefundamentalsofSmaart’ssingle‐anddual‐channelcapabilities,andprovideinstructionintheconfigurationandoperationofbasicmeasurementsetups.RegardlessofpastmeasurementexperiencewithpreviousversionsofSmaart,orotheranalysissystems,usersshouldtakethetimetofamiliarizethemselveswiththeprocessofConfiguringSmaartv7forMeasurementdetailedinthisdocument.Unlikepreviousversionswhichassumedasimpletwo‐channelI/O,Smaartv7caninterfacewithmultipleI/Odevicessimultaneously,eachwithmultipleinputandoutputchannels.Accordingly,Smaartv7makesnoassumptionsaboutauser’smeasurementrequirementsanduponfirstrun,beginsitsoperationun‐configured.Asinpreviousversionshowever,followinginitialsetup,Smaartretainsitsmeasurementconfigurationforsubsequentsessions.

Pleasenote:inthecaseofthefree/publicdemoversionofthesoftware,theSmaartmeasurementconfigurationisnotretainedfromsessiontosession,andmustbe

rebuiltforeachnewsession.Consideritpractice.Thisguideassumesareaderwithabasicunderstandingofprofessionalaudioequipmentandengineeringpractices.Itconcludeswithalistofrecommendedadditionalsourcesofinformationwhereuserscanfurthertheirunderstandingoftheseconcepts.

RationalAcousticsLLCisnotresponsiblefordamagetoyourequipmentresultingfromimproperuseofthisproduct.Besurethat

youunderstandandobserveproperinputandoutputlevels,impedancesandwiringconventionsofallsystemcomponentsbeforeattemptinganyofthemeasurementsdescribedinthisdocument.

©2009RationalAcousticsLLC.Allrightsreserved.

RationalAcousticsandSmaartareregisteredtrademarksofRationalAcousticsLLC.

TableofContents

GETTINGSTARTEDWITHSMAART®V7:BASICSETUPANDMEASUREMENT ................1

TableofContents .................................................................................................................................................... 2

GettingStarted:LoadingandLicensingtheSoftware ................................................................................ 3RecommendedComputerHardware ............................................................................................................................. 3RegisteringtheSoftware ..................................................................................................................................................... 3

FundamentalConcepts ......................................................................................................................................... 4Single‐Channelvs.Dual‐ChannelMeasurements...................................................................................................... 4TimeandFrequencyDomainAnalysis.......................................................................................................................... 5FFTs .............................................................................................................................................................................................. 6Smaartv7’sObject‐OrientedProgramArchitecture ............................................................................................... 7

ConfiguringSmaartv7forMeasurements ..................................................................................................... 7ConfiguringAudioI/ODevices ......................................................................................................................................... 8ConfiguringMeasurementGroups .................................................................................................................................. 9

TheSmaartv7GUI(GraphicalUserInterface) .......................................................................................... 11OperationModes...................................................................................................................................................................11GUIOverviews........................................................................................................................................................................11Navigation................................................................................................................................................................................13

SpectrumMeasurements .................................................................................................................................. 14SpectrumControls................................................................................................................................................................14RTA..............................................................................................................................................................................................15Spectrograph ..........................................................................................................................................................................15ApplicationExamples .........................................................................................................................................................16

TransferFunctionMeasurements ................................................................................................................. 19Magnitude ................................................................................................................................................................................19Phase ..........................................................................................................................................................................................20Coherence ................................................................................................................................................................................20TransferFunctionControls ..............................................................................................................................................21LiveIR ........................................................................................................................................................................................22DelayLocator/DelayTracking......................................................................................................................................22ApplicationExample:SettinganEqualizerforaLoudspeaker.........................................................................23

ImpulseResponseMeasurements ................................................................................................................. 25ImpulseResponseControls..............................................................................................................................................25Log/Lin/ETCViews .............................................................................................................................................................27FrequencyDomainView....................................................................................................................................................27IRModeSpectrograph ........................................................................................................................................................28

Appendices ............................................................................................................................................................ 28HotKeys....................................................................................................................................................................................29Self‐Help:WheretogoforAnswers..............................................................................................................................30RecommendedReading .....................................................................................................................................................30

GettingStarted:LoadingandLicensingtheSoftwareToinstallSmaartv7onacomputer,theuserrunstheWindowsinstaller(forWindowsOS’s)ordragsthesoftwareapplicationbundleintoyourapplicationsfolder(MacOS’s).

RecommendedComputerHardwareWhileSmaartv7willoperateonawiderangeofcomputerhardwareconfigurations,werecommendthefollowingminimumcomputerconfigurationfornewinstallations:

Windows®OperatingSystem:MicrosoftXP,VistaorWindows7(32&64‐bit)CPU:2GHzDual‐CoreIntelProcessororfaster(orcompatible)RAM:2GBorgreaterVideo:Graphicsprocessorwith128MdedicatedvideoRAM,minimum1024x600pixeldisplaySoundHardware:AudioHardwarewithOScompatibleASIO,Wav/WDMdrivers.

Macintosh

OperatingSystem:MacOSX10.5or10.6(LeopardandSnowLeopard)CPU:2GHzDual‐CoreIntelProcessororfaster(orcompatible)RAM:2GBorgreaterVideo:Graphicsprocessorwith128MdedicatedvideoRAM,minimum1024x600pixeldisplaySoundHardware:AudioHardwarewithOScompatibleCoreAudiodrivers.

RegisteringtheSoftwareFollowinginitialinstallation,onfirstrunofthesoftware,theuserispresentedwithanactivationscreencontainingthatcomputer’s10‐digit“MachineID”andisaskedforan“ActivationCode”toauthorizethisinstallation.ThisMachineIDisauniquecodeforthatidentifiesthatcomputer.Likewise,theActivationCodeisauniquecodethatwillonlyworkforthecomputerwiththatMachineID(muchthesameasSmaartLivev5’sPIC).Iftheinstallationisonacomputerthatisconnectedtotheinternet,theusercanchoosethe“ActivateOnlineNow”optiontoacquirethenecessarycodeandactivatetheinstallation.Otherwise,theusershouldmakenoteoftheMachineIDandaccessSmaart’slicensingsystemathttp://my.RationalAcoustics.comviaanothercomputertoacquirethenecessarycodetoactivatethisinstallation.Ineithercase,theusermustentertheirSmaartv7licensenumber(20alpha‐numericcharacters:XXXXX‐XXXXX‐XXXXX‐XXXXX),andthepasswordfortheuseraccounttowhichthelicenseisregistered.IftheSmaartv7Licensehasnotyetbeenregisteredtoauseraccount,theusermustfirsteithercreateanewaccountandpassword,orchooseanexistingaccounttoregisteritto(i.e.yourSmaart6licenseaccount.)EachlicenseofSmaartv7allowsfortwoinstallationsofthesoftware.UsersmaypurchaseadditionalinstallationsforanylicensebycontactingRationalAcousticsorauthorizedrepresentative.

Note:Smaartsoftwareislicensedtoasingle“user”–definedaseitherasinglepersonorcompany.Allsoftwareinstallationsforagivenlicensemustbeperformeduponcomputersownedbythatuser.

FundamentalConceptsDependingupontheapplication,operatingSmaarteffectivelyrequiresaworkingunderstandingofwiderangeofsystemmeasurementconceptsandprofessionalaudioengineeringpractices.Whileitisoutsidethescopeofthisdocumenttocoverthemall,thissectionhighlightsafewcriticalconceptsthatwillsignificantlyassistinunderstandingSmaartv7’soperationanditsapplication.Thisdocumentincludesanappendiceswhichhasalistofrecommendedadditionalsourcesofinformationwhereuserscanfurthertheirunderstandingoftheseconcepts.

Single‐Channelvs.Dual‐ChannelMeasurementsInitsessence,Smaartperformstwodistincttypesofmeasurement:single‐channel(signalanalysis)anddual‐channel(responseanalysis).Singlechannelmeasurementsexamineasignalatsinglepointinasystem,andcouldbestbedescribedassignalanalysismeasurements.Theseoperationsquantifyaspectslikesignallevelandfrequencycontent,andappearinSmaartasSpectrum(RTAandSpectrograph)andSPLmeasurements.Withsingle‐channel,theuseracquiresasignalviaanelectricalprobe(signalsplit)oranacousticalprobe(microphone),andexaminesthecontentofthatsignaldirectly.Single‐channelmethodsprovideanabsolutemeasurement,andhelptoansweranengineer’squestionslike“howmuch1kHzenergyisinthatsignal?”“whatisthatfrequency?”or“whatistheSPLatthisplaceinthevenue?”.Dual‐channelmeasurementscomparetwosignalsinordertoexaminetherelationshipbetweenthem.InSmaart’simplementations,wecomparetheinputsignalofasystem(reference)toitscorrespondingoutputsignal(measurement)toexaminewhatthesystemisdoingtothesignalsthatpassthroughit.Thesecouldbestbedescribedassystemresponsemeasurements,andinSmaart,werelyondual‐channelmethodstomeasurebothasystem’sfrequencyresponse(transferfunction)andimpulseresponse.Dual‐channelmethodsprovidearelativemeasurement(inputvs.output),andhelptoanswerquestionslike“whatisthecrossoverfrequencyinoursystem”“howmuchboost/cut?”or“whenistheenergyfrommymainspeakerarrivingatthemic?”Bothtypesofmeasurement,single‐anddual‐channel,areextremelypowerfultoolsfortheaudioengineerwhounderstandstheirindividualstrengthsandweaknesses–whounderstandwhattheyaremeasuring,andjustasimportantly,whattheyare

not.Fartoooften,baddecisionswhenusingananalyzeraretheresultofengineersconfusing/conflatingthesemeasurementtypes.InSmaartv7,themeasurementprocessbeginswiththe“group”configurationprocesswherewedictatewhatsingle‐channel(Spectrum)anddual‐channel(Response)measurementswewishtouse.

TimeandFrequencyDomainAnalysisAbasicunderstandingoftherelativestrengthsanddifferencesbetweenTimeandFrequencyDomainanalysisiscriticaltoleveragingthemeasurementpowerpresentedinSmaart.Asproblemsolvingengineers,theabilitytoexamineameasurementfrommultipleperspectives(domains)isextremelyusefulintheprocessofanalyzingasignalorsystemresponse.EachofSmaartv7’sprimarymodesofoperation(Real‐TimeandImpulseAnalysis)includebothTimeandFrequencyDomainmeasurementviews.TimeDomainanalysisrefersexaminingoursignalsandsystemresponseovertime.Atimedomainplot(amplitudevs.time)ofasignalprovidesaviewofthewaveform–acriticalviewforsoundeditors.Atimedomainviewofasystemresponse(impulseresponse)showsthesignaldelaythroughthesystem,andwhetheranylatearrivingmultiplesofthesignal(reflections/reverberence)arepresent. FrequencyDomainanalysisreferstoexamingoursignalsandsystemresponsesoverfrequency.Afrequencydomainplot(amplitudevsfrequency)ofasignalprovidesaviewofitsspectrum–anextremelyhelpfulviewwhenidentifyingtonalcontentorlookingforfeedback.Afrequencydomainviewofsystemresponse(transferfunctionorfrequencyresponse)providesanexcellentlookatthetonalresponseofasystemaswellasitstime/phaseresponsebyfrequency.Inthefigurebelow,anexcellentexampleofthepowerofutilizingbothtimeandfrequencydomainviewsforexaminingsystemresponseisclearlydisplayed.TheFrequencyResponsemeasurementdepictsaresponsewithaseriesoflinearlyspaceddipsandpeaksinitsmagnitudetrace(lowertrace).Howeverthatrippleisthesymptom‐thecauseofthisripplecanbeclearlyseenintheTimeDomainviewofthesystemresponse–anobvioussecondarrivalintheimpulseresponseisthesourceofthecombfilterrippleseeninfrequencydomain.

Figure1:TheFourierTransform­movingsignalsbetweenthetimeandfrequencydomains.Upper

exampleshowstheconversionbetweenatimesignal(voicesample)anditsspectrum;lowerexampleistheconversionbetweenanimpulseresponseandafrequencyresponse(transferFunction).

FFTsSmaartusesFastFourierTransforms(FFTs)andInverseFourierTransforms(IFTs)totranslatedatabetweenTimedomainandFrequencydomainviews.Ineffect,anFFTtakesasectionofaTimedomainwaveformandprovidesthefrequencycontentofthatselectedpieceofsignal.WhilearigorousunderstandingofthismathematicalprocessesisnotrequiredtooperateSmaart,itisusefultoappreciatetheinverselyproportionalrelationshipbetweendatainthetwodomains,whereFrequencyResolution=1/TimeConstant(FR=1/TC).Inotherwords,toincreasetheresolutionofspectrumdata,onemustuselargertimeslicesoftheinputsignal.OfparticularnotehereisSmaartv7’sdefaultFFTsettingforTransferFunctionmeasurements,MTW(Multi‐TimeWindow.)InsteadofusingoneFFTofasinglefixedlength,MTWusesmultipleFFTsofdecreasinglengthwithincreasingfrequency.Thisefficientprocessprovidestransferfunctiondatawithaconsistentresolutionofgreaterthan48thoctaveabove60Hzwithacoherencefunctionthatisincreasinglysensitivetolatereflectivedatainthehigherfrequencies.ThefigurebelowshowsacomparisonofthesametransferfunctionmeasurementmadewithMTWvs.asingle16kFFTsettings.NoticethatMTWFFThasbetterresolutionintheLFwhilethe16ktracehasexcessresolutionintheHF.

Figure2:TransferFunctions­MTWvs.Single16kFFT

Formoreinformationonthissubject,anin‐depthtreatmentofFFTscanbefoundintheSmaartLive®TechNote“FFTFundamentals.”

Smaartv7’sObject‐OrientedProgramArchitectureOneofthemostpowerfulaspectsofthenewSmaartv7platformisitsobject‐orientedprogramarchitecture.Effectively,theprogramisbuiltofmanyindividualcodemodulesthatarerunasindependent,inter‐relatedprograms(objects).Dataacquisitionishandledbytheinputmodule(s),single‐channelanddual‐channelmeasurementsarehandledbyindividualspectrumandresponseobjects,andthegraphingandGUI(graphicuserinterface)aretheirownseparateobjectsaswell.Thisarchitecturecreatesameasurementenvironmentthateasilyscalabletoauser’sindividualrequirements.Ineffect,youcanrunasmanysimultaneoussingle‐channel(spectrum)anddual‐channel(response)measurementsasyourPCandaudioI/O(Input/Output)hardwarewillallow.ThisalsomeansthatSmaart’smeasurementplotsareseparateobjectsfromthedatatheygraph.Theimmediatebenefitofthisrelationshipistheuser’sabilitytochangedisplayparameters(smoothing,banding,spectrographrange,coherenceblanking,tracecolor)ontheflywithouthavingtorecalculate/re‐measurethedataforthenewdisplayparameters.

ConfiguringSmaartv7forMeasurementsThemeasurementprocesswithSmaartv7beginswiththeconfigurationofsingle‐channel(spectrum)anddual‐channel(response)measurements.Thissectiondetailstheprocessandfunctionsinvolvedinconfiguringthesoftwareformeasurement.Unlikepreviousversionsofthesoftwarewhichassumedasimpletwo‐channelI/O,Smaartv7caninterfacewithmultipleI/Odevices,eachwithmultipleinputand

outputchannels.Accordingly,Smaartv7makesnoassumptionsaboutauser’sI/Ocapabilitiesandmeasurementrequirements,andsouponfirstrun,beginsitsinitialoperationun‐configured.Asinpreviousversionshowever,followinginitialsetup,Smaartretainsitsmeasurementconfigurationforsubsequentsessions.

Note:inthecaseofthefree/publicdemoversionofthesoftware,Smaart’smeasurementconfigurationisnotretainedfromsessiontosession,andmustberebuiltforeachnewsession.

Smaartv7isabletoacquireinputsignalsfromanydeviceswith.wav,CoreAudio,orASIOdriversthatarerecognizablebythecomputer’sOperatingSystem(OS).Infact,itcangrabmultiplesignalsfrommultiplesourcessimultaneously.(Note:onlyoneASIOsourcecanbeaccessedatatime)

WhenSmaartv7starts,theuserispresentedwiththissplashscreen.Whilethisisdisplayed,SmaartcheckstoseewhatI/OdevicesareavailabletoyourOS.ItisherethatSmaartbuildsitslistofinputdevices,andonceadevicehasbeendiscovered,itwillcontinuetoshowupforconfigurationinsubsequentruns–evenifitisnotconnectedatlaterstartups.

Note:WhileanI/OdevicemayshowupinSmaart’slistofconfigurabledevices,itmustbeconnectedtoyourcomputeratthetimeofstartuptobeaccessibleduringprogramruntime.

ConfiguringAudioI/ODevicesWhilethisconfigurationisnotrequiredtousedevicesincreatingandperformingmeasurements,I/Odevice(s)canbe“configured”bytheuserintheI/OOptionsdialog.Thisconfigurationcomprisesadjustingthedevice’ssamplerate,bitdepth,andassigningthedeviceanditschannels“friendlynames”‐namesthathelpusersidentifysignalsanddevicesastheyconfiguretheirindividualmeasurements.The“AudioI/O”OptionsDialogueisaccessedviathe“OptionsMenu”orbyusingthehotkeycommand[Opt+A](“HotKeys”areSmaart’sbuilt‐in,keyboard‐basedcommands). Figure3:OptionsMenu

Options:AudioI/Odialog

• Userselectsdevicefromthedrop‐downlist(populatedatstart‐up).

• Usercanassign“friendlynames”tothe

deviceandindividualchannels.

Note:Remembertopress[enter]aftertypingfriendlynames,ortheywillnotberetained.

ConfiguringMeasurementGroupsToperformmeasurementswithSmaartv7,ausermustconstructtheirmeasurementconfiguration.Remember,insteadofafixedmeasurementtopology,Smaartv7’sobject‐orientedarchitectureallowsausertoconfigureasmanysingle‐channel(Spectrum)anddual‐channel(Response)measurementobjectsastheywishfromtheAudioI/Ochannelsavailable.Moreover,thesemeasurementscanberuneitherindividuallyorsimultaneously,dependingupontheuser’srequirements.Inordertostructureandmanageourconfiguration,weorganizeourmeasurementsintoSpectrumandResponse“Groups.”Thisisaccomplishedinthe“GroupManager”OptionsDialogwhichisaccessedeithervia“OptionsMenu”,byusingthehotkeycommand[Opt+G],orbyclickingontheGroupManagerbuttonlocatedinthemeasurementcontrolsareaoftheuserinterface.FromtheGroupManagerDialog,auserdefinestheirmeasurementobjectsandorganizesthemintogroups.Theleftsideofthisdialogisdedicatedtoa“treeview”ofthemeasurementconfiguration.Hereoneviews/creates/copies/deletesSpectrumandResponsegroupsandviewsthe

Figure6:TheGroupManagerDialog­apowerfulinterfaceforconfiguring,controllingandadaptingourmeasurementsystem.

Figure5:GroupManagerButton

Figure4:Options­AudioI/O

individualmeasurementsassignedtoeach.Thistreealsoactsasthenavigation/selectorforthe“GroupTabView”ontheleftsideofthisscreen.Onceagrouphasbeencreated,ausercanselectitfromthetreeandaddameasurementtothegroupbyclickingonthe“NewInput”(Spectrum)or“NewPair”(Response)button.

Whenconfiguringanewsingle‐channelmeasurementwithinaSpectrumgroup,theuserselectsthedesiredI/Odeviceandinputchannel.Whenconfiguringanewdual‐channelmeasurementwithinaResponsegroup,theuserselectsthedesiredI/Odeviceanda“measurement”anda“reference”channelforthatobject.Inbothcases,thedrop‐downmenuswillshow“friendlynames”forthedeviceandinputchannelsthatwereconfiguredforthatdevice.

Note:Meas.AndRefchannelsforaResponsemeasurementmustbeselectedfromthesameI/Odevice.

Fromthe“TabView”sectionoftheGroupManagerdialog,ausercanorganizeeachmeasurementgroup;adjusttheorderthateachappearsinonthemainUI,changetheselectedinputsignals,set/changethenameandcolorforeachtrace,andconfigurelive“Average”measurements(usingthe“NewAverage”button.)LiveAveragesaremeasurementswhicharecalculatedfromaveragesofotheractivemeasurementsinthatgroup.EachmeasurementobjectconfiguredintheGroupManagerDialogisbasicallyacompleteSmaartmeasurementengineinitself‐eachwithitsowndefinablesetof

Figure7:InputButton­createsanewsingle­channelmeasurement. Figure8:NewPair­createsanewdual­

channelmeasurementobject.

Figure9:GroupTabViewsectionoftheGroupManagerdialogshowingliveaveragesetup

measurementparameters.Consequently,eachobjectinthegrouphasitsown“Tab”inthisviewwhereuserscanaddressthoseindividualmeasurementparametersifrequired.TheglobalandindividualcontrolofmeasurementparametersfromwithintheGroupManagershallbecoveredinmoredetailforeachtypeofmeasurementlaterinthisdocument.

Note:Whileitisrelativelyeasytoconfigureandsimultaneouslyrunmultipleresponsemeasurements,itisHIGHLYrecommendedthatnew(andevenexperienced)usersstartwithsimpleconfigurationsandbuildupslowlyastheygetusedtomanagingmultiplesimultaneousmeasurements.

TheSmaartv7GUI(GraphicalUserInterface)ThissectionprovidesabasictouroftheSmaartv7userinterfaceandreviewsitsprimarynavigationaltoolsandconcepts.Asthefeaturesetandfunctionalityofv7expands,thiswillalwaysbeanareaofcontinualenhancement,however,thestandardlayouts,navigationtoolsandparadigmsdetailedherewillstillpersist.

OperationModesSmaartoperatesintwodistinctmeasurementmodes:Real‐TimeandImpulseResponse.Whilebothmodeshavetheabilitytoactivelymeasureanddisplayfrequencydomainandtimedomaindata,thefundamentaldistinctionbetweenthesemodesistheiroperationalfocus.Real‐Timemodeisdesignedasanenvironmentforefficientlymeasuringandcapturingspectrumandresponsemeasurements–ofteninmultiples–specificallyoptimizedforin‐situsystemalignmentandmixengineeringwork.ImpulseResponsemodeisdesignedtoprovidearobustandintuitivesetoftoolsformeasuringandexaminingtheacousticalresponseofsystemsandenvironments.Smaartv7’sImpulseResponsemodehasbeensignificantlyexpandedfrompastversions(andwillcontinuetoexpand)toincludemuchofthefunctionalityfromtheSmaartAcousticToolssoftwarepackage.

GUIOverviewsThegenerallayoutoftheGUIforReal‐TimeandImpulseResponsemodes:

Figure10:TheSmaartv7Interface­Real­TimeMode

Figure11:TheSmaartv7UserInterface­ImpulseAnalysisMode

Eachmodecontainsa“ControlStrip”ontherightsideoftheinterface,andtheReal‐TimemodeincludesaDataStorageareaonitsleftside.Themajorityofeachmode’sGUIhoweverisdedicatedtotheplotarea.Theuppermostportionofthissectionisdevotedtoacursorreadoutthatdisplaysthecoordinatesofthemousecursorin

amplitude,frequencyortimeunits,dependingonthecharttype,whenthemousecursorispositionedoveranyofthemaindataplots.

NavigationTherearethreebasicelementsinnavigating,controllingandconfiguringSmaartv7:GUIviamousecontrols,menus/optiondialogs,andhotkeys.Inmostcases,therearemultiplewaysofcontrollingthesamefunction–thisisparticularlyimportantforusecaseswhereonemethodispreferableoveranother(e.g.auseroperatingonatabletcomputerwherekeyboardcontrolarenotconvenient.)Acomplete,currentlistingofthehotkeyfunctionsisalwaysavailableinthesoftware’shelpfiles.Thatsaid,Smaartv7’sGUIisbuiltformouse‐basedcontrolasitsprimaryinteractionmode–eitherthroughbuttonsanddatafieldsinthecontrolstripanddataareas,orthrough“clickanddrag”controlsinthedataplotareas.Manyofthevariouscontrolsforeachmodewillbecoveredinthespecificsectionsofthisdocumentthatdealwiththespecificmeasurementtypes.Herehowever,wewillcoverthecontrolsthatdealspecificallywithmeasurementandmodeselection,andviewcontrol.MeasurementSelection:Inthedatawindowsforbothmodes,theusercanselectthemeasurement/plottypethatisdisplayedineachwindowbyselectingadrop‐downmenufromtheplottypelabelintheupperleftcorneroftheplot.WindowLayoutSelection:Layoutselectorbuttonsinthecontrolstripsetthenumberofdatawindows(1or2)andinthecaseofTransferFunctiondisplays,toggledisplayoftheoptionalliveimpulseresponse(LiveIR)display.Whenoperatingwithasplitdisplay,oneofthetwomainchartsisconsideredtheactive,orselectedchart.Thecolorofthemarginssurroundingtheplotindicateswhichofthetwoiscurrentlyselected.

Note:TheControlStripandDataStorageareasintheRealTimeModealwayscorrespondwiththeactivedatawindowmeasurementtype.

DirectlyabovetheWindowLayoutbuttonsintheReal‐TimeModearetwobuttonsthatrecallstandard,pre‐setmeasurementviews.The“Spectrum”buttondisplaysasingleplotwindowwith“RTA”asthechosendatatype.The“Transfer”buttonsswitchestoatwo‐windowdisplaywithPhasedisplayedintheupperwindowandMagnitudeinthelower.

Figure12:PlotTypeSelectionforReal­TimeModeDataWindows

Figure13:WindowLayoutButtonsforReal­TimeMode

Figure14:Pre­SetViews

ModeSelection:UserscantogglebetweenmeasurementmodesusingeithertheModebuttonsinthecontrolstrip,viathe“Mode”menu,orbyusingthe[I]and[R]hotkeys.Zooming:Userscanzoominanyofthedatawindowsbyusinga“rubberband”zoombyeitherholding[command]+(leftbutton)clickinganddragging,or(rightbutton)clickinganddraggingazoomareaontheplot.Hotkeysarealsoavailableforzoomcommands.

Note:ClickingontheX(horizontal)orY(vertical)axisofanydataplotwillresetitszoomrangestodefault.

SpectrumMeasurementsSmaart’ssingle‐channelSpectrummeasurementsallowausertoexaminethespectralcontentofaudiosignalsthroughouttheirsystem.Thesemeasurementsareextremelyusefulinmanyapplications,includingthelocationoffeedbackfrequenciesinsoundreinforcement,noiseandsoundexposuremeasurements,cinemasystemoptimization,aswellasgeneralsignalmonitoringtasks.DatafromSmaart’sSpectrummeasurementsareviewableasastandardRTA(RealTimeAnalyzer)plots,orgraphedovertimeinathree‐dimensional(levelvs.frequencyvs.time)Spectrographplot.

SpectrumControlsOnceconfigured,individualSpectrummeasurementsappearaselementsintheSpectrumcontrolstrip.Here,theusercanchoosewhichmeasurementstoactivelyrun ,monitortheinputlevelofthesignal,andshow/hidethetrace.GlobalSpectrumSettings:Bydefault,allSpectrumobjectsusethesameglobal,user‐configurablemeasurementanddisplayparameters(FFT,Averaging,WeightingandScale).TheglobalScaleandAveragingsettingscanbeadjusteddirectlyfromtheSpectrum

Figure15:SpectrumControlStrip

ControlStrip,whileallglobalsettingscanbeaddressedintheGroupManagerdialog.Moreover,AveragingandWeightingcansetseparatelyforeachmeasurement(ifdesired)intheindividualmeasurement’stabintheGroupManagercontrols.

RTAThereal‐timeanalyzer,orRTA,isafamiliartooltoaudioprofessionals.Byadjustingthescaleandaveraging,auserisablerefinetheirmeasurement’sresolutionandresponsivenesstofitthetaskathand.

Figure17:SpectrumRTA­ScaleandAveragingAdjust

SpectrographWhiletheRTAhashistoricallybeen,byfar,themostcommonlyusedviewofaSpectrumforprofessionalaudioengineers,anotherwayofdisplayingthisdataisextremelyilluminatingandhasbeencommonlyappliedforyearsinthefieldsofvoicerecognition,vibrationanalysisandunderwateracoustics(onsubmarines).Smaart’sSpectrographdisplay(orSpectrogram,asitismoregenerallyknown)isaplotofasignal’sspectrumovertime.ThishybriddisplaygraphsacontinuousseriesofSpectrummeasurementswithfrequencyononeaxis,timeonanother,andlevelindicatedbythetracecolor.InSmaart,thisgraphisfundamentallygovernedbysettingthethresholdlevelatwhichdatabeginstoappearonthegraph.Whenafrequencybandinthespectrumisoverthelowerthreshold,itshowsupontheplot,startingwithadarkbluecoloratlowerlevels,andtransitioningthroughgreen,

Figure16:GlobalSpectrumSettingsfromGroupManager

yellow,orangeandredwithhigherlevel–eventuallyshowingupaswhiteifthelevelreachesorexceedstheupperthreshold.Thekeytocreatingausefulspectrographisinsettingthedynamicrangeforthedisplay–insettingthethresholdsforshowing/hidingthespectraldata.Settherangetoowideandthedisplaylosesdefinition,andimportantfeaturesmaygetlost.Setittoonarroworthelowerthresholdtoohighanddatamightgetmissedaltogether.OneofthepowerfulnewfeaturesinSmaartv7istheThresholdAdjustmentHandlesthatareavailableontheleftaxisofRTAandSpectrographplots.Withthesecontrols,ausercanadjustspectrographthresholdsdynamically–withouthavingtoreacquirethedata.Moreover,Smaartv7’sspectrographretainsahistoryofthelast“x”slices(spectrummeasurements),andausercanscrollthedisplaybackthrougholderdatainthehistoryifithaspassedoffofthedisplay.Ausercanaccessandadjustthesizeofthishistoryfile,aswellasthedisplaywidthforeachslice,intheSpectrumOptionsdialog.

Note:Smaartonlygraphsdatafromthe“active”spectrummeasurement–evenifmultiplesingle­channelmeasurementsarerunningsimultaneously.

ApplicationExamplesWhatfollowsaretwoexamplesofspectrummeasurementsusedincommon,“realworld”applications.ThefirstusesbothRTAandSpectrographforexaminingfrequencycontent–specifically,inidentifyingfeedbackfrequencies.Thesecondusesthespectrographtoexamineinteractionpatterns(combfiltering)thatarecausedbydirectsoundinteractingreflectionswithnearboundaries.FeedbackIdentification:

Figure18:SpectrographThresholds

Figure19:SpectrographSettingsinSpectrumOptions

Inthisexample,avocalmicrophoneisroutedthroughasimplesoundsystem.ForourSpectrummeasurementweacquiretheoutputsignalofthemixingconsole.Thevocalmicgainisraiseduntilwegetfeedback.

Thefeedbacktonecanbeidentifiedasaverticalbarat1.24kHzintheRTAdisplay.However,becausethereisalsoothersignalgoingthroughthesystematthesametimeasthefeedback,itiseasiertodistinguishtheverticallineoftheconstantfeedbacktoneintheSpectrographplot.

Figure21:FeedbackDisplayedinRTAandSpectrographPlots

Figure20:SystemConfigurationforMonitoringFeedback

ExaminingInteractionPatternswithSpectrograph:ThefollowingisasimpletechniquethatusestheSpectrographforexaminingcoverageandinteractionpatternsinloudspeakersystems.Simplyput,theuser

excitesthesystemwithpinknoise–whichshouldproducearelativelyconstantlevel/coloratallfrequenciesonaspectrographplot–andthenmovesthemeasurementmicthroughthelisteningenvironment.Levelvariationsfrominteractions,liketheaudiblecombfilteringcausedbyreflections,canbeseenasinteractionpatternsonthespectrographplotofthemicsignal.Adjustingthedynamicrangehelpstobetterhighlighttheinteractionpatterns.

Figure23:SystemConfigurationforInteractionStudy

Figure22:CombFilterInteractionPatternsViewedintheSpectrographPlot

TransferFunctionMeasurementsTransferFunctionisadual‐channelmeasurementthatdeterminesasystem’sfrequencyresponsebycomparingitsinputsignal(reference)toitsoutputsignal(measurement).Thismeasurementshowsthedifferencebetweenthosetwosignalsinbothmagnitudeandphaseandrepresentstheprocessingbehaviorofthesystemasafunctionoffrequency.

Smaart’sTransferFunctionmeasurementallowsausertoexaminethefrequencyresponseofvariouscomponentsoftheirsoundsystem,bothelectrical(EQ’s,mixers,processors)andelectro‐acoustical(loudspeakers,theirenvironmentandtheirdriveelectronics).Thesemeasurementsareextremelyusefulinmanyapplications,includingloudspeakerdesign,equipmentevaluation,equalizationandsystemoptimization.DatafromSmaart’sTransferFunctionmeasurementsareviewableasfourseparatetraces,onthreeseparateplots/windows:magnituderesponseandcoherence(samewindow),phase,andliveIR(timedomainplot).

Note:AstoredTransferFunctionmeasurementcomprisestheMagnitude,PhaseandCoherencetraces–LiveIRisnotcaptured.

MagnitudeTheMagnitudewindowshowsboththeMagnitudeportionofthetransferfunction(frequencyresponse),andtheCoherencetrace(seebelow).Inthemagnitudeplot,gainandlossshowupasdeviationfromthecenter0dB

line.

Theusercanclickanddragamagnitudetraceupanddowntomoveitverticallyontheplot.

PhaseThePhaseplotdisplaysthePhaseportionoftheTransferFunctionmeasurement.Thisplotshowsthedifference(indegrees)betweenthereferenceandmeasurementsignals,andprovidesanindicationofoverallrelativetimingbyfrequency,phaseshiftduetofilteringandsystempolarity.Thephaseplotis“circular”through360o–thetopoftheplot(180o)isthesameplaceasthebottomoftheplot(‐180o).Thephasetracebelowshowsacontinuoustracethatleavesthebottomoftheplotandcontinuesonfromthetop.

Theusercanclickanddragaphasetraceverticallytochangethepositionofthe0opoint.Regardlessofthepositionof0o,thephasetracealwaysdisplaysarangeof360oinitsstandard,“wrapped”displayformat.

CoherenceTheCoherencetracedisplaysthestabilityoftheTransferFunctiondataoverthegivenseriesofmeasurements/averages,andisexpressedasapercentagefrom0(badcoh.–inconsistentdata)to100%(highlyconsistentdata.)IftheTransferFunction’saveragerissetto“instantaneous”,Coherenceisnotcalculated.

TheCoherencetraceisplottedusingtheupper½oftheMagnitudewindow.Therearethreegeneralcausesofreducedcoherence.First,aproblemwiththemeasurementsystem–mostcommonly,nothavingthemeasurementdelaysetproperly(seebelow).Second,environmentalnoisecausingmeasurementcontamination–lossofsignal‐to‐noise.Andthird,excessreverberance/dropofDirect‐to‐Reverbratiointhemeasurementsystem.Onanongoingbasis,theCoherencetraceprovidesanexcellentindicationofsystemintelligibility,andisagoodsourceoffeedbackonsystem/measurementquality.

SmaartutilizesablankingfunctionthatwillhideTransferFunctiondatafromtheplotatfrequencieswhereCoherenceisbelowasetblankingthreshold.TheusercansetthisinTransferFunctionoptions,orusetheadjustmenthandleonthemagnitudeplot(nexttothecoherencescaleintheupperright).

TransferFunctionControlsLikeSpectrum,allTransferfunctionmeasurementsbydefaultusethesame“GlobalTFSettings”forFFT,Averaging,Smoothing,etc,‐unlesstheyaresettoignorethosesettingsinthemeasurement’sindividualtabintheGroupManager.

Averaging:Averagingameasurementstabilizesthemeasurementandhelpsrejectuncorrelatednoise.TheSmaartv7usesastandardFIFO(FirstIn,FirstOut)forthelowerlevelsofaveraging(2,4,8,16)andthenswitchestoaccumulatorsabovethat(1sec,2sec,etc).TheseaccumulatorsprovidesignificantimprovementsinstabilityoverpastlargerFIFO’sandarepreferredforacousticmeasurements.Smoothing

Smaartv7includesnew“FractionalOctave”smoothingalgorithmsforreducingtherippleinTFtracesandaidinginviewingthegeneraltrendsofthedatacurves.

LiveIRTheTransferFunctioncanbeviewedasa“LiveIR”.ThisdisplayshowstheImpulseResponseinalinearscale,timedomainviewwiththeTFmeasurementdelaytimelocatedatthecenterofthescreen.LiveIRsettingscanbeadjustedintheTransferFunctionOptionsdialog.

DelayLocator/DelayTrackingTransferFunctioniscalculatedbycomparingthesignaloninputtoasystemtoit’scorrespondingoutputsignal.Mosttimes,thereissomedelaythroughthesystem,oftentheresultoflatencyintheprocessing,signaldelayandacousticpropagationtime.Eachtransferfunctionobjecthasameasurementdelaythatcanbeusedtodelaytheinput/referencesignaltoitsoutput/measurementsignal.Accordingly,Smaarthasabuilt‐in“DelayLocator”functionthatperformsanimpulseresponsemeasurement,and

returnsthetimeassociatedwiththetallestpeak–normallythedelaytimeassociatedwiththearrivalofthedirectsound.Foreachmeasurementobject,thisfunctioncanbecalledwiththe“Find”buttoninitsindividualmeasurementcontrol.Alternatively,theusercanchoosetohaveanindividualmeasurementobjectcontinuouslytrackthemeasurementdelay(usingthesamebasicfunctionasLiveIR)bypressingthe“Track”buttonorindicatorlightlocatedinthemeasurement’sindividualcontrol.

Note:The“Track“functiondoesconsumesomeprocessorresources,soifyourmeasurementdelayisnotchanging(themicorspeakerisnotactivelymoving,)itisprobablybesttoturntrackoffoncethemeasurementdelayhasbeenacquired.

ApplicationExample:SettinganEqualizerforaLoudspeakerInthisexample,anengineermeasurestheTransferFunctionofaloudspeaker,andthenadjustsanequalizerto“flatten”itsoverallresponse.Here,theuserhasamulti‐channelI/O,someasurementsoftheEqualizer(MixOutcomparedtoEQOut)andcompleteloudspeakersystem(MixOutcomparedtoMicrophone)canbeperformedsimultaneously.Thisexamplecouldalsobeaccomplishedperformingthosemeasurementsindividually/sequentially.Thisexampleusesthefollowinghardwareconfiguration.

Thisconfigurationproducesthefollowinginitialmeasurements.

Nextwecapturetheloudspeakerresponsetrace,adjusttheEQandviewtheresultsintheactive“MicOne”measurementofthetotalsystem.NotethattheEQmeasurementhasbeensettographinverted,sowecanlaytheEQdirectlyoverthestoredresponsetrace.Thishelpswithrefiningfilterwidthandfrequency.

ImpulseResponseMeasurementsImpulseResponsemodeisdesignedtoprovidearobustandintuitivesetoftoolsformeasuringandexaminingtheacousticalresponseofsystemsandenvironments.Smaartv7’sImpulseResponsemodehasbeensignificantlyexpandedfrompastversions(andwillcontinuetoexpand)toincludemuchofthefunctionalityfromtheSmaartAcousticToolssoftwarepackage.Inthismode,wecanalsoanalyzepreviousIRmeasurements(orothertime‐domaininformation)thathavebeenstoredinstandard.wavor.aiff(MAC)audiofileformat

ImpulseResponseControlsInIRMode,ausercanperformanImpulseResponsemeasurementbychoosinganyResponseMeasurementtheycurrentlyhaveconfigured,settingthemeasurementparameters(primarilyFFTsize/TC),acquiringsignalsandpressingstart.Alternatively,theusercanchoosetoloadastoredfileviathe“File”menu.Oncetheuserhascapturedorloadedanimpulseresponsemeasurement,theycanusetheviewingtoolsbelowtoanalyzeit.AtthetopoftheIRmodeGUIisawindowdisplayingtheentireimpulseresponseinlinearview.This“Nav”windowisusedforselectingthetimedomainzoomforthelowerdatawindows.AsinReal‐Timemode,rightClickanddragtochooseyourzoomwindow,andclickonthedataaxistoclearthezoom.

Note:Whenmeasuringanimpulseresponse,itisveryimportantthatyouhaveastrongreferencesignal(givethemeasurementagood“view”ofthesignalyouarelookingfor),andmakesureyourTCissettoatleastfivetimes(5x)thelengthofthetotalsystemresponse(includingreverberantdecay)youaremeasuring.

Log/Lin/ETCViews

FrequencyDomainView

IRModeSpectrograph

Appendices

HotKeysMeasurement Controls

[O] Selected Measurement On/Off

[Cmd/Ctrl] + [O] All On (run all live measurements of selected type)

[Cmd/Ctrl] + [Alt] +[O] All Off (stop all llive measurements of selected type)

[V] Reseed Averages

Delay Controls

[D] Track Delay (toggles Delay Tracking for selected Transfer Function measurement)

[Cmd/Ctrl] +[D] All Track (turn on Delay Tracking for all active Transfer Function measurements)

[L] Find Delay (for selected Transfer Function measurement)

[Cmd/Ctrl] + [L] Find All Delays (find delays for all active Transfer Function measurements)

[,<] Increment Delay (for selected Transfer Function measurement)

[.>] Decrement Delay (for selected Transfer Function measurement)

Data Storage and File Operations

[Space] Capture Trace (captures the front trace on the selected graph into the selected storage slot)

[Cmd/Ctrl] + [F] Capture and File Trace (creates a permanent file on disk while capturing)

[Cmd/Ctrl] +[S] Save to File (.wav or .srf/trf depending on the operating mode)

[Del] Clear Selected Storage Slot

Display Controls

[I] IR Analysis Mode

[R] Real-Time Mode

[S] Spectrum

[T] Transfer Function

[Cmd/Ctrl] + [I] Live IR (Show/Hide)

[Y] Clear Y Offset (Selected)

[Cmd/Ctrl] + [Y] Clear Y Offset (All)

[Z] Cycle Z Order (Forward)

[Shift] + [Z] Cycle Z Order (Back)

[+] Zoom In Y

[–] Zoom Out Y

[Cmd/Ctrl] +[+] Zoom In X/Y

[Cmd/Ctrl] +[–] Zoom Out X/Y

[Cmd/Ctrl] + [Alt] +[+] Zoom In X

[Cmd/Ctrl] + [Alt] +[–] Zoom Out X

[Up Arrow] Scroll Up*

[Down Arrow] Scroll Down*

[Left Arrow] Pan Left

[Right Arrow] Pan Right *Or roll "roll" the (wrapped) Phase display. [Cmd/Ctrl] means press the [Ctrl] key on a Windows computer or the [Cmd] key (sometimes called the Apple Key or "flower" key) on a Macintosh computer. The Alt key on a Windows system maps to the Option key on

Self‐Help:WheretogoforAnswersUltimately,theuser,asengineerandoperator,isresponsibleforansweringtheirownspecificapplicationquestions.Inordertoassistinthisprocess,RationalAcousticssuggeststhefollowingsources:

1. UsetheHELPFILESinthesoftware–alotofveryhelpfulinformationaboutSmaart’sfunctionsandfeaturesisthere,anditisfullysearchable.

2. TheSmaartuserforumsatRationalAcoustics.com3. SmaartTrainingsessions4. PreviouslypublishedSmaartandSmaartLiveManualsandTechnical

Notes–thesecanbefoundontheRationalAcousticswebsiteat:http://www.rationalacoustics.com/pages/New_Documentarium

5. The“RecommendedReading”sourcescitedinthelastsectionofthisdocument.

6. OrevencontactRationalAcousticsdirectlyviaemail(preferred)orphone.

TrainingsessioninformationandcontactinformationforRationalAcousticsandauthorizedrepresentativescanbefoundathttp://rationalacoustics.com.

RecommendedReadingD.Davis,C.Davis:SoundSystemEngineering,2ndedition.Carmel,IN:SAMS.1994.M. Mehta, J. Johnson, C. Rocafort: Architectural Acoustics: Principles and Design.

UpperSaddleRiver,NJ:PrenticeHall.1999.AmericanNational Standard: Specification for Sound LevelMeters, ANSI S1.4‐1983.

NewYork,NY:AcousticalSocietyofAmerica.1983.R. Cabot, B. Hofer, R. Metzler: Standard Handbook of Video and Television

Engineering: Chapter 13.3: “Nonlinear Audio Distortion”, 4th edition.McGraw‐HillProfessional.2003.

OSHA Standard: Occupational Noise Exposure, OSHA 1910.95. Washington, DC:

OccupationalSafety&HealthAdministration.1996.

Criteria foraRecommendedStandardOccupationalNoiseExposure,RevisedCriteria1996,DHHS(NIOSH)PublicationNo.96.Atlanta,GA:NationalInstituteforOccupationalSafety&Health.1996.

Motion­Pictures ­ B­Chain Electroacoustic Response ­ Dubbing Theaters, Review

RoomsandIndoorTheaters,SMPTE202M‐1998.WhitePlains,NY:SocietyofMotionPictureandTelevisionEngineers.1998.

If you have an interest in furthering your knowledge of the engineering concepts behindFFT‐basedmeasurement,youmayfindthefollowingtextsuseful:

A.Oppenheim,A.Willsky,S.Nawab:SignalsandSystems,2ndedition.UpperSaddleRiver,NJ:PrenticeHallInc.1997.

A.Oppenheim,R.Schafer,J.Buck:Discrete­TimeSignalProcessing,2ndedition.Upper

SaddleRiver,NJ:PrenticeHallInc.1999.