In 1892, physician Achille Gouguenheim (1839–1901) was invited to teach a course on the physiology and hygiene of singing at the Paris Conservatoire. By that time, scientists had been interested in the mechanics of the ‘invisible’ singing voice for years, initially experimenting on human and animal cadavers using strings and weights to make dead larynges sing. By mid-century, with the development of better quality artificial lighting and mirrors, physicians and physiologists finally developed a better understanding of the relationship between voice and physiology. Meanwhile, by 1890, a growing number of connoisseurs and medical professionals alike were concerned that there was a crisis ruining French operatic singing. Gouguenheim and others argued that the key to improving the situation rested on embedding medical knowledge and its relationship to the proper functioning of the larynx and voice into pedagogy at the Conservatoire. Drawing upon archival documents, debates in leading periodicals and Gouguenheim’s published lecture notes, we examine the marriage between medical science and artistic pedagogy during the latter part of the nineteenth century. Overall, we argue that this evidence reveals a strand of French vocal training that merged the fields of science and artistry, if ever so briefly, creating pedagogical methods that for a few years offered the promise of rescuing French opera performance.