The soprano problem is the mispronunciation of lyrics by sopranos at the high end of their range. In order to make themselves heard in opera houses, sopranos need their voices to resonate, which they only do when making certain sounds.
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.
A pair of scientists have found that the meticulous Richard Wagner may have been aware of this problem and wrote the soprano parts in his operas to minimize the mispronunciations.