帮我翻译这篇文章。谢谢。Apainterhangshisorherfinishedpicturesonawall,andeveryonecanseeit.Acomposerwritesawork,butnoonecanhearituntilitisperformed.Professionalsingersandplayershavegreatresponsibilities,forthecomposerisutterlydependentonthem.Astudentofmusicneedsaslongandasarduousatrainingtobecomeaperformerasamedicalstudentneedstobecomeadoctor.Mosttrainingisconcernedwithtechnique,formusicianshavetohavethemuscularproficiencyofanathleteoraballetdancer.Singerspracticebreathingeveryday,astheirvocalchordswouldbeinadequatewithoutcontrolledmuscularsupport.Stringplayerspracticemovingthefingersofthelefthandupanddown,whiledrawingthebowtoandfrowiththerightarm—twoentirelydifferentmovements.Singersandinstrumentshavetobeabletogeteverynoteperfectlyintune.Pianistsaresparedthisparticularanxiety,forthenotesarealreadythere,waitingforthem,anditisthepianotuner’sresponsibilitytotunetheinstrumentforthem.Buttheyhavetheirowndifficulties;thehammersthathitthestringhavetobecoaxednottosoundlikepercussion,andeachoverlappingtonehastosoundclear.Thisproblemofgettingcleartextureisonethatconfrontsstudentconductors:theyhavetolearntoknoweverynoteofthemusicandhowitshouldsound,andtheyhavetoaimatcontrollingthesesoundwithfanaticalbutselflessauthority.Techniqueisofnouseunlessitiscombinedwithmusicalknowledgeandunderstanding.Greatartistsarethosewhoaresothoroughlyathomeinthelanguageofmusicthattheycanenjoyperformingworkswritteninanycentury.