Hermann von Helmholtz (1821 94) was a leading scientist who made important contributions to physiology, psychology, physics, philosophy and early neuroscience. Following his foundational work in ophthalmics during the 1850s, he became Professor of Physiology at Heidelberg and, in 1863, published On the Sensations of Tone. This investigation into the physical theory of music remains a central text for the study of physiological acoustics and aesthetics. In it, Helmholtz applies physics, anatomy and physiology. He explains how tones are built from a base tone with upper partial tones, and his...