The first time I ever heard "Matona, Mia Cara" I knew the lovely Italian Renaissance text was entirely beyond my comprehension, but musically I felt I'd heard enough choral music to feel like I had some sense of what I was hearing anyhow.
I was wrong.
"Matona Mia Cara" was written by Orlande de Lassus, a sixteenth-century composer who was not himself Italian, though the piece was written in that language... badly. The Italian of the lyrics is terrible, and deliberately so. The song's viewpoint character is a German soldier during the Italian Wars, and his words to Matona are full of grammatical errors, faux-unintentional double entendres, innuendo, and irony. To an Italian audience of the sixteenth century, presenting this as a serious German love song and then singing "mi ti portar becacce, grasse come rognon" would have been the height of comedy.
All too often, however, modern audiences are either given a translation into well-written English or no translation at all. But it doesn't have to be this way - I once conversed with a gentleman who had been part of a group which sang the song with somebody holding signs with English subtitles, written in the same style as the original Italian words while translating it more or less accurately. "Me go hunting in woods," they read during one verse. "Me bring you back cock. Me bring you back BIG cock." The audience was in stitches, just like the sixteenth-century ones would have been.
"Authenticity" is an elusive and highly sought-after quality, especially in the performing arts and related media. But all too often the focus is on the performer's authenticity, and the authentic experience of the audience is not even considered.
In the world of Baroque music, "authentic performance" can involve the use of period instruments, meantone tunings, tuning pitches other than A440, layouts of the musicians based on Baroque-period imagery, vocal styles with less vibrato than modern art music, and more. The most authentic performance possible of "Matona Mia Cara," however, is unlikely to involve subtitles as innuendo-laden as the Italian text. We do not expect monoglots to read Beowulf in the original Anglo-Saxon, but instead suggest our favorite translations (mine is Dick Ringler's). The commedia dell'arte troupe I perform with does not perform in late sixteenth-century Italian but modern English (occasionally with modern jokes thrown in). Yet old songs are often performed in ways equally incomprehensible to modern audiences!
In folk music circles today, on the other hand, authenticity is no less desired, but it comes from a sense of continuity with the distant past rather than an attempt to recreate it. The history of folk traditions is marked by constant gradual change, and there is nothing inauthentic about using a guitar with a flat pick in any English-language folk tradition today. Old pieces that are still well-loved are often played in modern styles, as in this version of a Foster melody, without any loss of accuracy. Since the audience is usually part of the same culture that produced the performance, it is able to comprehend what is being presented exactly as intended.
But when it comes to historical folkways, that comprehension is often lost. A little bit of that is inevitable - while a modern audience can be told a novel story about Robin Hood that is enriched by their familiarity with the teller's source material, most modern American audiences will find stories about Bernaldo del Carpio unfamiliar and foreign. Yet those stories can still be presented in a way that is entirely comprehensible, and not in any way strange to them - it just requires careful selection. A ballad about the Count of Saldaña that is replete with foreshadowing about the birth of Bernaldo will be lost on an audience who doesn't already know Bernaldo's significance and backstory, but Lockhart's "March of Bernardo del Carpio" is quite accessible. So far as I am concerned, the watchword should be "foreign, but not strange"; performance of something outside the audience's experience will always introduce them to something unfamiliar, but it should be presented in ways that resonate with what they are accustomed to so they can more fully absorb what they see and hear.
It is with a similar aim in mind that I work on my poetic translations. After all, the most authentic possible recitation of a Spanish poem is in Spanish, with historically accurate pronunciation (which is sufficiently well-studied to be easily doable), but an English-speaking audience will hear nothing but the rhyme and the flow of the meter. Those purely linguistic qualities are changed or lost if the poem is recited in English instead, so the task of the translator is to preserve them as nearly as is accessible to an otherwise-uncomprehending audience. But something much more important is gained, if the audience is able to understand a work that would otherwise have been opaque to them. This is seen as entirely normal where poetry is concerned, but in music, it seems to have fallen out of favor sometime in the 20th century.
It wasn't always this way. Old modal folk melodies are often only preserved in the Ionian and Aeolian versions that appealed to their collectors' audiences (who grew up on music of the common practice era) rather than the Mixolydian and Dorian forms that seem to have been common in days gone by. I applaud the fact that they were adapted to the musical ears of those intended to listen to them next, but it's unfortunate that the earlier versions have often been lost. Performance styles of current folk traditions continue to evolve (indeed, outside of music, it's not uncommon to see sword dance notations with a disclaimer about how they reflect a particular moment in the life of an ever-adapting tradition and should not be mistaken for directives on how the dance ought to be performed in later years), and even museums presenting material culture try to make sure the audience has a sense of its place in life.
So far as I am concerned, the only way to present a piece of music as authentically as possible is to pay equal attention to the authenticity of the audience's experience as to the details of what sounds are produced.
This is not a call to throw away accuracy in the name of accessibility. Rather, I think it is important for performers to sacrifice as little of both as they possibly can. This is far more demanding than giving up on either in service to the other, but it is important work, and the results are quite rewarding - I can listen to Owain Phyfe singing music by Richard the Lionheart all day, because he knows how to play in a style that reflects the music's medieval heritage but resonates with the folk traditions to which I am accustomed. He knew his material, his audiences, and his own skill, and he provides enough explanation to understand despite the foreign lyrics. I'd like to see more people willing to attempt such a feat, and if I'm very lucky I'll get to see someone who manages to maintain greater levels of both accuracy and accessibility in their performance even than Phyfe. Only when both the accuracy needed to properly present history and the familiarity needed to bring the audience into the performance are paramount does it become possible for the presentation of old material to pull the audience into the work's original context and bring history alive.