The project investigates the link, developing in the period from 1850 to 1900, between the psycho-physiological study of hearing and the cultural history of hearing and listening, in particular the practice of hearing or listening to music. Its point of departure is Hermann von Helmholtz’ theory of “tonal sentiments” (Tonempfindungen), which servedas the physiological basis of his theory of music; Helmholtz developed this idea both as a physiological basis for the theory of hearing/listening and a foundational concept of music theory. Rather than conceiving of The Theory of Tonal Sentiments (Die Lehre von den Tonempfindungen) as a work that attempts to connect fundamentally discrete contributions to various disciplines such as musicology, acoustics, physiology, and psychology and at the same time seeks to heal the split between “two cultures” through interdisciplinarity, this project proceeds from the hypothesis that Helmholtz was presenting a unified and self-contained concept. It asks to what extent music itself can be conceptualized as an experimental system that significantly impacts the development of Helmholtz’ theory. For Helmholtz, even composition, insofar as it develops its own system of rules, is characterized by experimentation: it is the analytical capability executed by the ear, by means of which musicians and composers decide what aesthetic relationships between sounds are permissible. If music was indeed always a science and worked with experiments, then it was Helmholtz who introduced physiological research into its parameters. The ear, which is simultaneously an instrument of measurement and an organ, is responsible for the selection and combination of musical acoustic events. Helmholtz’ theory can thus be summed up as follows: in it, music theory and composition are conceived and reformulated as disciplines that work experimentally. Helmholtz’ theses about the foundations of music theory can thus be unified with the postulates of music theory, but they also open up a space for intervals that had no place in the music of the nineteenth century. Music in the laboratory thus encounters other ways of hearing and listening that would be developed in the music aesthetics of the twentieth century.