It all began as a battle. The "authentic" or "original instruments" movement, as it was called in the 1970s and 80s, claimed modern orchestras did not produce the sounds composers such as Bach, Mozart, or Beethoven would have known.
Advancing technology in the 19th century had made all instruments more powerful and accurate. But modern instruments just didn't sound right to authenticists such as Christopher Hogwood, who set up his Academy of Ancient Music to play on instruments with the designs and sounds of earlier times. The movement was at first obsessed with following exact markings on musical scores and banishing the rich modern orchestral sounds thought out of place. Critics responded by lambasting what they saw as a clinical approach to musicmaking, and characterized the sounds as "vinegary" or "astringent."
The two sides are finally coming together in a spirit of cooperation, however, at England's premier summer opera festival. The Glyndebourne Festival gives modern listeners an opportunity to judge for themselves. There, the period Orchestra of the Age of Enlightenment (OAE) shares musical duties with the modern-instruments London Philharmonic. Each orchestra is assigned a number of the six productions to perform each season.
John Christie, a wealthy country-estate owner, opened the first opera season at Glyndebourne in 1934. Mr. Christie sought complete evenings of grace and beauty, and so the tradition arose of formal dinner dress for the audience, who would enjoy picnics on the lawns during extended performance intermissions. Glyndebourne, with a tuxedo dress code and most tickets priced at $210, still calls up the image of a jewel-bedecked dowager. But in using both period and modern orchestras, the festival is pursuing one of the most innovative experiments in today's world of opera.
Period-instrument performers explain why their presence is relevant to the understanding and enjoyment of opera. The 19th century brought a more flowing singing style in which the meaning of the words became less important than the beauty of the sounds, explains Christopher Kreuger, Baroque flutist and UMass Amherst professor.
Improved technology, such as in the violin bow, resulted in seamless phrasing that's still taught today. New orchestra pits removed musicians from the immediacy of the drama on stage.
The sound world of the 18th century was quite different, drawing from the Greek ideal of surpassing nature with art. "We were told to imitate the voice to see if wood and metal and hair could be as beautiful as the natural instruments," says Marshall Marcus, violinist and chair of the OAE.
Eighteenth-century bows were less developed at the tip, with the result that sound tended to fade and rise, giving it a speechlike character. Gut strings also produce more immediate and cleanly projected sounds, giving greater control of gestures and phrasing.
This aesthetic is matched in other orchestral sections. Unlike modern flutes, with their rows of keys to produce difficult notes, Baroque flutes require complex finger patterns, and this creates a different timbre for every note. Even Baroque timpani share the aesthetic, producing a more rapid-fire sound, one that lends itself to shaping and phrasing, according to OAE timpanist János Keszei.
The highly characterful period instruments have a natural way of coming together. For example, the composer Glück often requires winds and strings to play passages of the same notes. Period instruments can do this without the conflict often associated with more strident modern instruments.
While instrumental virtuosity was valued in the romantic era of the 19th century, emotional coloration was more important in earlier Baroque opera.
To Gerald Finley, the Agamemnon in the Glyndebourne production of Glück's "Iphigénie en Aulide," "the quality of the cat gut gives that purity of tone which reaches our ear almost unconsciously and gives emotional tension without drawing attention to itself."
Boston Handel & Haydn Society Baroque oboist Marc Schachman says that "if you learn to play an old instrument, it teaches you how to play itself.... It tries to speak another language."
Louis Langrée, who conducts both period- and modern-instruments orchestras and leads the London Philharmonic in this season's Glyndebourne performances of Don Giovanni, is among those who believe that the language learned with period instruments can be passed to modern ones.
The period-instruments movement came in at the same time as nouvelle cuisine, but you can also "remove the fat" from modern ensembles while preserving the good taste, says Mr. Langrée. Vibrato can be pruned back, phrases shaped for maximum clarity.
Langrée has no qualms about mixing and matching, and has the Philharmonic play Baroque trumpets and timpani for "Don Giovanni" at Glyndebourne because he could not get the right effect from modern instruments. "When they play, I want them to play full power because it's music of the inferno."
His approach showed its strengths this summer in a vivid, free-flowing "Don Giovanni." Strings were crisp and clear, capturing the violence, the heartbeats, and the humor of the opera with period-instruments-style precision.
The Glyndebourne experiment has shown there is not just one musical path. "Authenticity does not exist," Langrée says. "What is more important is the spirit."