[1] Richard Cohn's eagerly anticipated monograph on nineteenth-century chromaticism crystallizes Cohn's decades of influential work developing an analytical framework for chromatic harmony. It also fulfills the need of presenting a self-contained, accessible introduction to Cohn's theory, one that will be of great value to readers less receptive to the mathematical orientation of many of the articles that mark essential milestones in the development of Cohn's theories. But Audacious Euphony also goes further, marking a stride forward in the unification of Cohn's theories and their extension into new analytical concepts and techniques that promise to be widely influential in future work on nineteenth-century harmonic practices.(1)[2] The first half of Audacious Euphony follows the general contours of the historical development of Cohn's thinking about chromaticism. He begins, in Chapter 1, by advancing the non-integrationist argument, that nineteenth-century chromaticism is not simply an extension of Classical harmonic practice, which has been a persistent theme of his work beginning with Cohn 1996. In particular, Cohn argues that chromatic harmony is based on the logic of the consonant triad in chromatic space, and is therefore independent from Classical harmony, in which triadic relationships are mediated by diatonic scales. Chapter 2 introduces hexatonic regions, the topic of Cohn 1996, while chapters 3 and 4 develop the idea of Weitzmann regions as companions to hexatonic regions, the subject of Cohn 2000. The ultimate goal of these arguments is the unified model of between consonant and augmented triads, Douthett and Steinbach's (1998) Dancing Cubes network. Cohn similarly united hexatonic cycles and Weitzmann regions in Cohn 2000, but in Audacious Euphony, the idea has noticeably matured. Most importantly, Cohn follows Tymoczko (2009) in recognizing Cube Dance as a faithful model of distance, unlike, e.g., the Tonnetz (84-85). From this other significant properties emerge, such as the cyclic arrangement of sum classes, which Cohn dubs voice-leading zones (102-6).[3] In parallel with the construction of the Cube-Dance model of triadic relationships, Cohn also develops the technology of neo-Riemannian transformations, in particular the Tonnetz, the subject of his highly influential Neo-Riemannian Operations, Parsimonious Trichords, and their Tonnetz representations (Cohn 1997). Yet the superficial impression that Cohn might simply be consolidating his legacy of transformational approaches to chromatic harmony by collecting fifteen years worth of work in one volume turns out to be wholly inaccurate. Cohn's perspective on the Tonnetz and neo-Riemannian transformations, like his use of Cube Dance, has thoroughly evolved since he helped to shape Lewin's (1987) system of transformations into one of the most significant recent developments in music theory. In order to bring the Tonnetz model and Cube Dance together in a unified perspective on relations between triads, Cohn outfits the Tonnetz with new accessories that mitigate its shortcomings as a model of distance: hexatonic strips (27-30) and augmented-triad alleyways (84-85).[4] Cohn also essentially divests himself of the dualist commitments implicit in neo-Riemannian transformations. Although he defends dualism (37-39), it is no longer a deep theoretical principle. He does not, as Riemann himself might have, claim that dualist nomenclature reveals a deeper musical truth of inversional equivalence; instead he makes a purely formal argument that dualist transformations reflect the fact that distance is independent of direction.[5] To repurpose one of Cohn's favored descriptions of Schubert's chromaticism, Audacious Euphony marks a soft revolution in the deployment of the Tonnetz. While a persistent surface feature of a music theory tradition that spans over two centuries, in Cohn's hands the meaning of the Tonnetz has undergone a radical shift. …