MIT OpenCourseWare http://ocw.mit.edu24.910 Topics in Linguistic Theory: Laboratory PhonologySpring 2007 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.PraatNotes 10/11/06EdwardFlemmingPraatBasicsOpeningafiley Goto‘Read’menu,select‘readfromfile…’o Filenameshouldappearintheobjectswindow,prefacedby‘Sound’Viewingwaveformsandspectrogramsy Highlightthenameofthesoundfileintheobjectswindow.y Clickthe‘Edit’buttonontherightoftheobjectswindow.o Thisopensaneditwindow,withawaveformandspectrogram.y Clickanddragtohighlightaportionofthewaveform.y Clickonthebarsbelowthespectrogramtoplay.o Bottombarplaysthewholefile.o Middlebarplaysthewholewindow.o Topbarisdividedbycursorplacement.Eachsectionplaysthecorrespondingportionofthewindow.y Tomovebackwardsandforwardsinthefile,usetheslideratthebottomofthewindow.y Zoominandoutusingthebuttonsatbottomleft:o ‘all’zoomsouttodisplaythewholefile.o ‘in’and‘out’zoominandout,respectively.o ‘sel’zoomstoahighlightedsectionofthewave.F0analysis,intensity,andformanttrackingy Therearemenusfor‘Pitch’,‘Pulses’,‘Intensity’and‘Formant’.Theseanalysescanbeselectedorturnedofffromthesemenus.y Settingfortheseanalysescanbealteredusingoptionsfromtherelevantmenus.Adjustingthespectrogramy Thespectrogramcanbealteredusingoptionsunderthe‘Spectrum’menu,in‘Spectrogramo Settings’and‘AdvancedSpectrogramSettings’.y Ifyouareseeingalotofbackgroundnoiseinyourspectrogram,decrease‘dynamicrange’under‘SpectrogramSettings’.ThissetsthedBrangebetweenblackandwhiteinthespectrogram.Blackisautomaticallyassignedtothehighestintensityinthevisiblewindow,soalowerdynamicrangeimpliesahighercut‐offforenergyatafrequencytobeplotted.40‐50dBisgenerallyappropriate.y Togenerateanarrowbandspectrogram,increasethewindowlengthunder‘spectrogramsettings’.Defaultis0.005s(quitebroadbandwidth).0.02sorlongermayberequiredtoresolveharmonics.Editingwaveformsy Cut,copy,andpastecommandsareunderthe‘Edit’menuoftheEditwindow.y Tomakecutsandjoinsatzerocrossings,use‘Move…tonearestzerocrossing’commandsunderthe‘Select’menu.y Tosavesectionofafile,highlightthesection,gotothe‘File’menu,select‘Writeselectionto<type>file’.o Youcanalsouse‘Extractselection’–thissetsuptheselectionasanewSoundobjectintheobjectswindow,butdoesn’tsaveitasafile.o Tosaveanewobject,highlightitintheobjectwindow,gotothemain‘Write’menu(atthetopofthescreen),andselectappropriate‘Writeto…’command.y Changesarenotsaveduntiltheeditedrecordingiswrittentoasoundfile:highlightthenameintheobjectwindow,gotothemain‘Write’menu(atthetopofthescreen),andselectappropriate‘Writeto…’command.MeasuringformantfrequenciesusingPraatformanttracksPRAAThasaformanttrackingalgorithm.Theresultsaredisplayedoverthespectrograminaneditwindowif‘showformants’ischeckedunderthe‘formant’menu.Youcangetanumericalread‐outforanypointonthetrackusingtheprocedurebelow.1. Identifythetimepointwhereyouwouldliketomeasuretheformants.Foramonophthong,thiswillusuallybeneara‘steadystate’intheformanttrajectories,ornearthemiddleofthevowel.y Foradiphthong,youmayneedtomeasuretwopoints,oneearlyinthevowel,andtheotherlate,butdon’tmeasureformantstooclosetoadjacentconsonants,becausetheconsonantscanhaveastronginfluenceonformantfrequencies.(Note:theconsonant[h]generallyhaslittleinfluenceonformantfrequencies,soitisusuallyOKtomeasurenear[h]inwordslike‘how’and‘hide’).2. Twowaystoobtainformantfrequencies:y Clickontheformantpeakatyourchosentimepoint.Thisproduces‘cross‐hairs’onthespectrogram.Thefrequencyisprintednexttothehorizontalcross‐hair,attheleftofthespectrogram.y Clickonthetimepointwhereyouwanttomakemeasurements.UsethefunctionkeysF1,F2tobringupwindowsshowingtherespectiveformantfrequencies.o Note:Thismethodisgivingyouthefrequenciesofthereddotsmarkedonthespectrogram.Thesearegeneratedbyanautomaticformanttrackingalgorithm.ITCANMAKEMISTAKES,soalwayscheckthatthedotslookreasonablebeforeusingthesefiguresandadjusttheformanttrackingparametersasnecessary.3. Adjustingparametersoftheformanttrackingalgorithm.y Theformanttrackingalgorithmhastwokeyparameters:o
View Full Document