In this article, I propose a musico-cultural analysis of expressions of vulnerability in the connections between musical interval, linguistic texture, and language. I focus on the productive qualities of the in-between space of the voice within a specific interval—the falling semitone—and demonstrate how the exaggerated use, repetition, and reverberations of this interval by two Belgian musical artists, Jacques Brel (1929–1978) and Stromae (b. 1985) contribute to a cartography of vulnerability particular to their aesthetic projects and cultural critiques. This analysis places Michel Serres’ philosophies of communication and Roland Barthes’ grain de la voix into dialogue with an examination of the aural in-between. The exaggerated repetition of the semitone is heard as an undulation reminiscent of a melisma (several notes sung over one syllable), which is mirrored in the embellished trilled [R] consonant particular to these two artists. Visualizing the shared melodic and linguistic acoustic movements as undulations provides a point of access into the in-between space of the sung voice that reframes weakness, failure, and vulnerability as highly choreographed and exploited central aesthetic projects shared by Brel and Stromae.