When physicist John Smith spent the night in his garden with the score to Götterdämmerung, the final opera in Richard Wagner’s four-part, 15-hour epic, Der Ring des Nibelungen, he wasn’t interested in its account of the apocalyptic struggle of Norse gods for control of the world. Smith was concerned with a struggle of a different sort—one between the opera’s words and music that might elucidate the controversial German composer’s peculiar vision for the future of art.
On Smith’s mind was an age-old difficulty all soprano singers face: They mispronounce lyrics when singing powerfully in the top half of their range. This “soprano problem” was formally recognized at least as far back as 1843, when French composer Hector Berlioz wrote in his Treatise on Instrumentation that “[sopranos] should not be required to sing many words on high phrases, since this makes the pronunciation of syllables very difficult if not impossible.” It does not appear, however, that Berlioz—or anyone else—ever understood why this problem occurred.
In 2004, Smith and his colleagues Joe Wolfe and Elodie Joliveau at the University of New South Wales published a study in the Journal of the Acoustical Society of America that revealed the physiological cause of the soprano problem for the first time. They sent an acoustic signal through the vocal tracts of nine sopranos and used a microphone to measure how the signal changed when the sopranos sang vowel sounds at various pitches. They found that when a soprano sings at high pitches, she adjusts her vocal tract to make her voice resonate. In effect, she “tunes” the resonance frequency of her vocal tract to match the frequency of the pitch at which she is singing. This vocal-tract tuning, which gives a soprano’s voice enough power to fill an opera house, is what makes certain words at high pitches difficult for the audience to understand. (It is joked by singers that Wagner’s character of Siegfried in Der Ring des Nibelungen ought to have been called Sahgfried, as his name is sometimes pronounced that way by sopranos looking to get the most volume out of their voices.) Jane Eaglen, a critically acclaimed soprano who has performed Wagner’s works in opera houses worldwide, explains that sopranos must try to find a balance between power and clarity. “It’s really about how you modify the vowels at the top of the voice so that the words are still understandable but so that you are also making the best sound that you can make,” she says.