This article argues that each new development in sound technology is accompanied by a mismatched woman — a figure with a voice that fails to gel with the image of her body. Because they are famous for having singing voices that startle listeners with their beauty and dexterity and, importantly, because they are unable to reproduce, such women owe their popularity to the legacy of the castrato. Castrati, the original mismatched voices, were known not only for their skill, but also for their mythology, which perpetuated tales of both sexual prowess and impotence, longevity and early death, and male and female personality traits. By examining the career of one mismatched woman, Deanna Durbin, I revisit film theory's reliance on discourses of synchronicity and patriarchy to account for the female voice in cinema. I show how Durbin's celebrity is dependent on a developing conception of adolescence and expose the mismatch as a zone of liminality that can be confined to neither the diegesis nor the father. The instability of Durbin's voice is exemplified by the two halves of her cinematic oeuvre. Prior to US entry into the Second World War, Universal presented Deanna Durbin as a young operatic ingenue with European roots who remains a child in spite of her mature vocal skill. After the beginning of the war, however, her films unsuccessfully attempted to transform Durbin into an American seductress capable of performing in a range of styles even as the studio and her fans were simultaneously promoting her image of eternal adolescence. Throughout Durbin's career, the standardization of playback as a means of producing Hollywood musical numbers guaranteed that viewers would always be reminded of the time of the music's recording, a moment exposed in her early films in which Durbin was distinctly, and forever, a girl.