Olga Neuwirth’s Orlando (2019) reimagines Virginia Woolf’s gender-fluid protagonist across five centuries, intertwining feminist critique and postmodern aesthetics. This article explores how Neuwirth sonically enacts the concept of ‘in-betweenness’, aligning with Deleuze and Guattari’s philosophy of becoming. Neuwirth constructs an ‘androgynous sound’ through hybrid styles, pop-cultural references, and the countertenor voice. Focusing on four pivotal duets, the analysis shows how vocal registers, textures, and stylistic ruptures destabilize gender norms and formal expectations in opera. I argue that Orlando transcends its narrative framework, positioning opera as an active space of knowledge production and political resistance. Tracing sonic gestures from Woolf’s literary modernism to Neuwirth’s contemporary score, I reveal how operatic voices carve out a sonic Borderland where gender and identity are not merely performed but continuously invented.