"Une si profonde simplicité" : Mireille (1906-1996) et la naissance de la chanson française moderne: This article focuses on the figure of Mireille Hartuch (1906–1996), a singer-songwriter known as Mireille. In addition to providing a detailed account of her career, the article focuses on her style in order to highlight her decisive contribution to the changes that took place in French chanson at the end of the Roaring Twenties. For this reason, the corpus studied consists mainly of recordings from the 1930s. Mireille’s music is analysed using a combination of sources and methods: transcriptions of original recordings are used in conjunction with scores found on “petits formats” (commercial scores deposited at the BnF); traditional musical analysis is combined with new computer methods (vocal isolation, sonograms). This methodological mix makes it possible to approach the analysis of popular and commercial songs from a musicological perspective, without abandoning the analysis of what is, after all, a musical text, the centrality of performance, or the historical, aesthetic and cultural questions raised by songs marked by the imprint of American music.