No scholarship yet exists on Erin Gee’s extensive Mouthpieces catalogue, aside from her own program notes and non-academic reviews of her work. My dissertation endeavors to remedy this gap through analyses of two formative works by Gee, Mouthpiece I (1999/2000) for solo voice and SLEEP (2008), an opera in 12 scenes for two voices, choir, and mixed ensemble. This dissertation is the offspring of two seemingly disparate theoretical influences: Pierre Schaeffer’s Traité des objets musicaux and Marion A. Guck’s definition of analysis as interpretation. In Chapter 1, I introduce Schaeffer’s reduction to the objet sonore as an analytical methodology, then interrogate the pros and cons of this method through the lens of feminist and post-humanist scholarship as well as sound studies focusing on vocal physiology. Chapter 2 considers the historical legacy of experimental non-semantic vocality in the United States, and considers how Afrodiasporic vocal techniques in jazz and gospel weave their way into Eurodiasporic experimentalism generally and Gee’s music in particular. I also ask why these hugely prevalent genres in both commercial and academic music circles fail to be included in standard scholarly narratives of non-semantic vocality in the United States. In Chapter 3, I propose an idiosyncratic typology and typomorphology for Mouthpiece I as an analytical framework for understanding the building blocks of Gee’s music more generally. I than take a broader look at the relationship between form and materials in SLEEP to consider how Gee intertwines semantic and non-semantic vocality to replace the operatic norms of high drama and individual virtuosity with an intimate, collective sonic ecology that presents both human and non-human on stage at the same time.