This chapter argues that, throughout the 1870s, literary understandings of voice were transformed by, and also helped to shape, acoustic technologies and sciences. Developments in physics and physiology, and the invention of the telephone and the phonograph at the decade’s end, offered new ways of describing how the human voice was formed, transmitted, and heard. However, these developments also reimagined voice as something not exclusively human, continuous with a wide spectrum of inarticulate and non-human sounds. This dehumanisation threatened to undermine established definitions of literary voice, but literary and scientific writers also identified similarities between their respective theorisations of speech and sound, and ‘voice’ became a keyword that was frequently used to examine the wider relations between science and literature. After discussing George Eliot’s views on the possible implications of new vocal technologies for prose fiction, the chapter turns to the sonnets of Emily Pfeiffer, which examine how scientific models of voice might complicate and reimagine poetry’s conventional status as the most essentially vocal of literary forms.