Interfacingthetxalaparta:digitisingatraditionalinstrumentwiththehelpofitsplayers
EnrikeHurtado
UniversityoftheBasqueCountry,Bilbao,[email protected]
Abstract.ThispaperdescribestheprocessofcreatingsoftwareforgenerativemusicthatincorporateskeyelementsoftheBasquetxalapartainstrument.Thisispartofanongoingresearchprojectwhichstudiesthisancientmusicaltradition.Traditionally,thetxalapartaisplayedasimprovisationbyatleasttwoplayersandinthisresearchprojectwehavedevelopedasystemthatallowsaplayerandacomputertoplaytogether.Thispaperdescribestheuser-centeredapproachinthesoftwaredesignexplaininghowthisinfluencedthesolutionsandissuesaddressed.Theresearchwaswidereachinginitsuserstudies,anditprovideduswithadeeperinsightonthetxalapartaplayandthe-implicitorunexpressed-rulesinvolvedintheinteractionbetweenplayers.
Keywords:txalaparta,generative,interface,interaction,participatorydesign.
IntroductionThetxalapartaisapercussiontraditionoriginalfromtheruralareasoftheBasqueCountry.Theinstrumentbelongstothecategoryofstruckidiophonesandconsistsofavariablenumberofwoodenplanksplacedhorizontallyontwotrestles,andbeatverticallywithrelativelyheavywoodenbatons.Planksmadeoutofothermaterialssuchasironorstonearealsocommon.Thetxalapartaisplayedbyatleasttwoplayerswhoalternatetheirbeatstoconstructthebarperformingthroughanimprovisatorycall-and-responsepattern.
Thetxalapartaandtheavant-gardewererelatedduringthe60sand70s(Hurtado,2015a),andlikemanycontemporarymusicalcompositionssincethe50s,itsplaycanbeunderstoodasaprocessdefinedbyaseriesofinstructionsthattheplayersuseasguidelinetoimproviserhythms.Infact,manyauthorsandinterpretersclaimthatwhenreferringtothetxalapartawearediscussingtherulesandtherhythmgeneratedmorethanthephysicalinstrumentitself(Escribano2012,4;Beltran1988,198).
Sincethelate80s,theinstrumentandthewayitisplayedhaveundergoneanormalizationprocess,called“xylophonisation”byEuba,whereitstraditionalpercussivenaturehasshiftedtowardsamelodiconewiththeplanksbeingtuned(2004,32)andtherhythmaccommodatedtothestandardwesternmusiccanon.However,theoldstyleofplayingisstilllearntandusedbymany.
BackgroundThetxalapartahasnotbeenthesubjectofacademicresearchuntilveryrecently.Escribano(2012)andGambra(2008)haveexploredculturalandacousticalissueswhileEuba(2004),andSanchezandBeltran(1998)havefocusonthemusicalaspect.Also,somepractitionersprovideanintroductiontotheplayinganddescribetheinstrumentandthetraditionsaroundit(Beltran2004;Beltran,2009;Goiri,1996)andtherearereferencesfromanthropologistsandmusicologistsatthebeginningoftheXXcentury(Azkue1906;Lecuona1920;Donostia1924;Barandiaran1934).
Figure1.TheUgartebrothersplayingtxalaparta.PicturebyXabierEskisabel
Someattemptstoproducesoftwarebasedonthetxalapartahavebeendevelopedbeforeus.Intheearly90s,TecnotxalapartawasdevelopedattheLaboratoriodeTratamientodePalabrayMúsicainMadrid.Thissoftwarewasabletolistenandrespondtothehumaninterpreteradjustingitstempoinreal-time.TheinputwasdonewithkeystrokesinakeyboardandthecomputeroutputwasMIDI.Tecnotxalapartawasneverreleased.Later,Ixiaudioreleasedanapplicationwherebydraggingfoursticksaroundtheinterfacetheuserwasabletocontrolanongoingtxalapartarhythm.Morerecently,appearedTtakun,asequenceraimedatcreatingcompositionsandexercisesforthetxalaparta.Finally,TxalapartappfortheiOSallowsoneormanyuserstoplaytxalapartabytouchingthescreen.Therearealsoprojectssimilartooursbutthatfocusonotherinstrumentsandtypesofmusic.Tonamesome:TheContinuator(Pachet2002),ImprovGenerator(KitaneandKoike2010),GenJam(Biles2002),Haile(Weinberg,DriscollandParry2005),RoboticMarimbaPlayer(WeinbergandDriscoll2007)orShimon(HofmanandWeinberg2011).OtherrelevantprojectsfocusonpopularmusicfromEthiopia(Herremans,Weisser,SörensenandConklin2015)orTalmusicfromthenorthofIndia(WrightandWessel1998).
Softwaredevelopment:ResultsWetriedtounderstandandformalisetherulesofthetxalapartaplayandtodevelopsoftwarethatreflectsthose.Weaimedatproducingapplicationsthatcouldrunonastandardlaptopsandtheresultwastwodifferentpiecesofsoftware.Thefirstone,calledAutotxalaparta,isasemiautomaticgenerativesoftwarethatfollowssimilarrulestothoseusedbytxalapartainterpreters(Hurtado2015b,124).Itgeneratesbothpartsofthetxalapartarhythm(thetwoplayers)andagraphicalinterfaceallowstheusertocontroldifferentparametersoftheprocess.TheAutotxalapartacanalsobeusedtoproduceonlyonepartoftherhythmthusallowingtoplayarealtxalapartaontop.However,thereisnointeractioninvolvedandthehumanhastofollowthemachine.Wedevelopedasystemtosequenceandautomatethemainparametersinthesystem.Thisallowedformorecontrolbutitdidnotallow,either,forrealtimecontrolwhileplaying.
Figure2.TheInteractivetxalapartasoftware
ThesecondsoftwareiscalledInteractiveTxalaparta.Itlistenstothehuman’splayinatxalapartausingthemicrophoneinputanddistinguishesthedifferentphrasesplayed,infersthetempoandprovidesresponsesthatfollowthehumanplay.Italsodetectsthenumberofhitsoneachphrase,theamplitudeofeachhit,theintervalbetweenhitsandwhichplankeachhitstrikes.ThesystemrespondstothehumanusingdifferenttechniquessuchasMarkovchainsandweightedrandomchoices.TheMarkovchainshaveoftenbeenusedtogeneratemelodies(Patchet2002),butheretheyareusedtodeterminethenumberofhitstheanswerphraseshouldcontain.Weightedrandomchoicesareusedtodecidewhichplanksareplayedintheanswer.Answerscanbebuiltintwomodes,thefirstonebuildsthephrasebygeneratingitsvalues(amplitude,intervals,etc...),whilethesecondonereusesinformationfrompreviouslyplayedphrases,thusbeingmorerealistic.Bothmodesfollowtheplayer'slastphrase’smeanamplitudeandmeanintervalsbetweenhits.Bydoingsothesystembehavesclosetohumanplayers,whoareinconstantnegotiationtokeeptherhythmgoing.CurrentlytheInteractiveTxalapartadoesnotproposenewideasorsituationsasitsmaineffortistoadaptandfollowthehumanconsistently,stillbeinglimitedinthestylesoftxalapartaplaythatcanunderstandandproducetorespond.Theinformationwiththeplayedphrasescanbesavedintoatextfileallowingforlaterfeedingtheapplicationwithdatathatreflectscertainplayingstylesorrules.
ParticipatorydesignandfeedbackfromplayersTxalapartaplayershadanimportantroleinthedevelopmentaswecontactedthemfromveryearlyonintheprocesstogetfrequentfeedbackonthesoftware,butalsotolearnaboutthelatesttrendsontxalaparta.Welookedforexperiencedplayerswithanopenmindedattitudetowardsnewideasandinnovationsandwescheduledmeetingsatkeystageswithintheprocess.Themeetingswerelaidbackonetoonetalkswerewereviewedthecurrentstateofthesoftwareandtesteditoutwhilewritingdownideas,suggestionsanderrorstheplayerwouldpointout.Occasionallywemadechangesinthecodeinsitu,iftherequestortheerrorweneededtosolvewaseasytoimplement.Wetriedtogetplayersinvolvedinthedevelopmentasmuchaspossibleandoneofthemactuallyattendeduptofourofthosemeetingsatkeypointsintheprocess.
Figure3.BeñatIturriozplayingwiththeInteractiveTxalaparta
Asaresultofthisuserorientedapproachwedetectedandfixedmanybugsandproblemsinthesoftware,butmoreimportantly,weidentifiedkeyideasthat,webelieve,wewouldhaveneverforeseenotherwise.Forinstance,duringtheearlydevelopmentoftheAutotxalaparta,playersexpressedtheirinterestinimprovisingtxalapartawiththecomputerassecondplayer,somethingwesimplydidnotexpect.LatertheypointedoutthattheyfeltstructuresgeneratedbytheAutotxalapartaweretoorandomand“nonhuman”.Torespondtothisissue,wedecidedtodevelopasystemthatwouldadapttothehumanallowingforaninteractiveimprovisatoryplay:theInteractiveTxalaparta.Inthiscasetherealinstrument,thetxalaparta,effectivelybecomestheinterfacetocontrolthesoftware,asthesoftwareadaptstothehumanplay.TheInteractiveTxalapartawasadirectconsequenceofthefeedbackandtherequestsreceivedfromtxalapartaplayers,anditmighthaveneverbeenenvisionedotherwise.
Apartfromtheinvaluablefeedbackonthedevelopmentcyclewejustbrieflydescribed,themeetingsprovideduswithaveryinterestinginsightonthetxalapartaplay.Theyshapedourunderstandingofthetxalaparta,butmoreinterestingly,theyalsoshapedtheunderstandingoftxalapartathatplayersthemselveshad.Thefactthatplayerswere,forthefirsttime,improvisingwithamachineinsteadofahuman,madethemself-awareandconsciousofmanyaspectsofthetxalapartaplay,andthewayplayersinteracttoeachother,thatwerepreviouslytakenforgranted.Theysaidtheyfounddistressing,forinstance,notbeingabletoseethearmsandbodyofthesecondplayer.Thisseemstobecrucialforthetxalapartaplayastheyrealisedtheyforeseetheactionsofthesecondplayerinthepositionandmovementofthebodyandarms.Inourcase,becauseoftheabsenceofabodywhileplayingwithacomputer,theysometimesfoundtherhythmgeneratedbythemachinedifficulttounderstand.Thisissueinfluencedthesoftwaredevelopment:toovercomeit,wedesignedgraphicalrepresentationsofthecomputer'srhythm.Themaingraphicalaidsdevelopedareacircularanimation1thatrepresentstheeventsplayedinthecurrentbarandapiano-rolltimeline.Inthefirstonethecurrentbarisrepresentedasacirclewiththephrasesofboththehumanandthemachinebeingdisplayed,thehitsdrawnasdotsfollowingclock-wisedirection.Sizerepresentsamplitude,positionrepresentstiming,humanproducedhitsareredandmachinehitsareblue(seecirculargraphicinthecentreoffigure2).Thesecondgraphicalaidisapiano-rolltimelinewherethepercussiveeventsanditsmaincharacteristics,suchasplayer,amplitude,timeandplankaredisplayedinreal
1InspiredonadiagrambySanchezandBeltran(1998)
time(seetoppartoffigure2).FuturedevelopmentsshouldincludethepossibilitytosavethedatadisplayedinthetimelineasMIDIforfurtheranalysisortobeusedwithinasequencer.
Playerssaiditwasveryinterestingtoplaywithbothprogramsbutintheiropinionthesoftwareisstillquitelimitedstylistically,astheInteractiveTxalapartacanonlyunderstandacertaintypeoftxalapartastyleandrhythms,andbothprogramscanonlygeneratealimitedstyleoftxalaparta.Weobservedthatsomeinterpretersoccasionallyusedthesoftwaretogetresponsessuchthatnohumanwouldproduce.Theyalsoplayedaroundwiththeerrorsthesystemproduced.Theseplayerssaidtheyfoundstimulatingwhenthesoftwareplayedclosetothelimitsofwhatcanbeconsideredavalidtxalapartarhythmorwhenitdidsomethingthatnotxalapartaplayerwouldeverdo.WepresentedanearlyversionoftheprogramsattheTxalapartaConferenceinPamplonainMarch2015wheremostattendantsthoughtthesoftwarewouldbeusefulbecauseitallowstoimprovisetxalapartawithoutasecondplayer.Attendantswerealsoveryinterestedinthequestionsonthenatureofthetxalapartaplaythatthesoftwareraisesandthathavepointedoutabove.Finally,wewouldliketomentionthatinthisongoingresearchontxalaparta,wehavecarriedoutthefirsteversurveyonit.Thiswasanonlinesurveywithquestionsonthetxalapartaandthechangesithasundergone.Itmainlyfocusedonqualitativedataandprovidedusveryinterestingdatathatcomplementedmanyaspectsofourresearch,butthatfalloutofthescopeofthispaper.
ConclusionsandfutureworkWehaveproducedtwocomputerprogramsbasedonthetraditionaltxalaparta.Oneofthem,theInteractiveTxalaparta,canbecontrolledbyplayingarealtxalapartaandallowsplayers,forthefirsttime,toimprovisetxalapartawithacomputerasthemachinegeneratesresponsesthatfollowtheuser’splaywhilelearnsandadaptstoit.Thecloseinvolvementoftxalapartaplayersduringthedevelopmentprovedcrucialasitallowedustoreachunforeseenresultsaswellastoidentifykeyideasandconceptsonthematter.Thisalsoprovideduswithadeeperunderstandingofthetxalapartaplayanditsmaincharacteristics.Futureworkshouldincludethedevelopmentofmorefunctionalandcompletesoftwarethatwouldallowtoanalysefurtherthetxalapartaplay.Thisshouldimprovethealgorithmsthatanalysethehumanplaytoallowformorestylesoftxalapartaandrhythmicaltechniquestobeunderstoodbythesystem.Wewillalsoimprovetheanswersystemtogeneratemorecomplexandrichrhythms,aswellasclosertothecomplexityofthehumanplay.Weplantoproduceacrossplatformversionoftheprogramsthatwouldallowustoreachabiggernumberoftxalapartaplayers.Thiswouldprovideuswithamorevariateandsystematicfeedbackfromtheplayersonthesoftwarewehavedeveloped.
AcknowledgementsThisresearchhasbeenpossiblethankstothesupportoftheElhuyarandtheUniversityoftheBasqueCountry(theArtandTechnologyDepartmentandtheMikelLaboaKatedra).
ReferencesAzkue,ResurrecciónMaría.1906.DiccionarioVasco-Español-Francés.Bilbao.
Barandiaran,JoséMiguel.1934.Euskaleŕi’koleengizona.Donostia:BeñatIdatziak.
Beltran,JuanMari.1988.“Txalaparta.AurreraBegira.”UdakoEuskalUnibertsitatearen1.988.ekoIhardunaldiak,181-200.Beltran,JuanMari.2004.Latxalaparta,antecedentesyvariantes.Delosritmosdetrabajoalamúsica.Oiartzun:Herrimusikarentxokoa.Beltran,JuanMari.2009.Txalaparta.Donostia:Nerea.
Beltran,JuanMari,andFranciscoJoseSanchez.1998.“Unateoríanuméricadelritmoaplicadaalatxalaparta.”Txistulari,no.173:27–43.
Biles,John.2002.“GenJaminTransition:fromGeneticJammertoGenerativeJammer.”GenerativeArt2002Conference.
Donostia,JoseAntonio.1924.“ApuntesdeFolklorevasco,Toberas.”RevistaInternacionaldeEstudiosVascos15:1–18.
EscribanodelMoral,Maria.2012.“RhythmsofStruggle.Recovery,RevivalandRe-CreationofTxalapartaintheBasqueCountry.”Ph.D.diss.,UniversityofLimerick.
Euba,Argibel.2004.“Txalaparta.TranscriptionandAnalysis.”Unpublishedwork.GoldsmithUniversity,London.
Gambra,Anai.2008.“RelaciónentrelafrecuenciafundamentalpropiadeunatabladeIroko(Chlorophoraexcelsa)ysusdimensiones:Aplicaciónalatxalaparta.”Master’sthesis,EscolaTècnicaSuperiord’EnginyeriaAgrària.
Goiri,Josu.1996.Txalaparta.Losdossonidosdelcorazón.Arrigorriaga:JosuGoiriIturrizar.
Herremans,Dorien,StéphanieWeisser,KennethSörensen,andDarrellConklin.2015. “GeneratingstructuredmusicforbaganausingqualitymetricsbasedonMarkovmodels.” ExpertSyst.Appl.42(21):7424–7435.
Hoffman,Guy,andGilWeinberg.2010.“Gesture-basedhuman-robotJazzimprovisation.”ICRA.IEEE,582–587.
Hurtado,Enrike.2015a.“Txalapartayvanguardia,ruidoymúsica”.Ausart3(2).Hurtado,Enrike.2015b.“Latxalapartadigital:Unanálisisdelatxalapartaatravésdeldesarrollodesoftware.”Ph.D.diss.,FineArts,UniversityoftheBasqueCountry.
Kitani,KrisMakoto,andHidekiKoike.2010.“ImprovGenerator:OnlineGrammaticalInductionforOn-the-FlyImprovisationAccompaniment.”NIME.nime.org,469–472.
Lecuona,Manuel.1920.“LasToberas.”EuskaleŕiarenAlde:RevistadeCulturaVasca10(194):41–43.
Pachet,Francois.2002,September.“TheContinuator:MusicalInteractionwithStyle.”EditedbyICMA,ProceedingsofICMC.ICMA,211–218.
Weinberg,Gil,andScottDriscoll.2007.“TheDesignofaRoboticMarimbaPlayer-Introducing PitchintoRoboticMusicianship.”NIME.nime.org,228–233.
Weinberg,Gil,ScottDriscoll,andMitchellParry.2005.“Haile–Aninteractiverobotic percussionist.”ICMC.
Wright,Mathew,andDavidWessel.1998.“AnImprovisationEnvironmentforGeneratingRhythmicStructuresBasedonNorthIndian“Tal”Pattern.”ICMC.
