This practice-led research investigates orality as a methodological framework for constructing authenticity in documentary filmmaking through the concept of “Voice-as-a-Method.” Drawing on personal material and the production of the short film Un Vague Souvenir (2026), the study explores how spontaneous spoken narration can be integrated into the development of voice-over. Situated within documentary theory and informed by scholars such as Bill Nichols, Michel Chion, and Paul Ward, the research interrogates authenticity as a constructed, relational effect shaped by performance, narrative structure, and audience perception. Through five iterative experiments—ranging from unscripted voice recordings to structured and performed narration—the study identifies a productive tension between spontaneity and formal coherence. The findings demonstrate that neither pure orality nor fully scripted narration alone sustains perceived authenticity; instead, a hybrid approach emerges as most effective. This approach, defined as “structured improvisation with semantic anchors,” allows the voice to retain its oral, performative qualities while operating within a flexible narrative framework. The paper ultimately proposes Voice-as-a-Method as a practice-led toolkit that foregrounds performance, embraces the instability of authenticity, and enables filmmakers to balance intuitive expression with intentional construction in the pursuit of a more embodied and affective documentary voice.