Nineteenth-century histories of human-animal aurality have typically centred on questions of animal ‘music’ in which music shores up the identity of being ‘human’ as much as human listening authenticates the value of what music is or should be. Being animal became an index for calibrating through sound the higher value of being human (Gautier 2014; Zon 2017; Mundy 2018).

Against this impulse, in this talk I trace an intersection of natural scientists and music theorists that posed a different kind of question: when did the penny drop that animal aurality was quantifiably different to humans? And could this difference be calculated, even simulated for human listeners? Attempts by nineteenth-century physiologists Johannes Müller and Karl Ernst von Baer, alongside the Leipzig theorist Moritz Hauptmann, offer case studies in the attempt by European naturalists and musicians to understand animal hearing. These mostly took the form of thought experiments that sought to re-quantify space and time. In this paper, I revisit these experiments in relation to Richard Wagner’s famous depiction of animal-human communication in Siegfried where the phenomena of polychronic listening and drug use, as mechanisms for altered perceptual realities, becomes recontextualised within discourses of nineteenth-century comparative anatomy and debates over human/animal identity.