We are struck by the place music occupies in our lives: a growing place, judging by the number of festivals and concert halls attended, the widespread downloading of recordings and the omnipresence of music in public places. Ancient Greek philosophers considered music essential to understanding nature, and gave it a prominent place in education. Based on the relationship between the length of a string and the pitch of the note it produces, Pythagoras of Samos developed a mathematical theory of musical harmony, which the Pythagoreans extended to the movement of celestial bodies, under the famous name of "harmony of the spheres".
In his 1868 treatise Physiological Theory of Music, Hermann von Helmholtz developed the first systematic, modern description of musical perception, based on the principles of physics and the then-new knowledge of cochlear anatomy. Remarkable for its scope, this theory introduces a resonance mechanism within the cochlea to explain the spectral analysis of sounds; it interprets the phenomenon of dissonance by the perception of beats appearing when the sound wave contains harmonics of slightly different frequencies, breaking the Pythagorean harmony relationship. Helmholtz's reductionist approach characterizes most subsequent work aimed at elucidating the physical basis of the functioning of the auditory organ. It should be borne in mind, however, that this viewpoint, in which cochlear physiology takes precedence, says almost nothing about the neural bases of hearing, and therefore gives a very imperfect account of the data arising from the study of musical perception. Towards the end of the 1960s, several initiatives led to the development of interdisciplinary research on music, notably with the opening in France in 1969 of the Institut de recherche et coordination acoustique/musique (Ircam), founded by Pierre Boulez. Around 2000, as the study of mouse models of hereditary deafness led to the renewal of cochlear physiology, the physiology of musical perception entered the scene, with advances in functional imaging enabling the activity of auditory pathways to be probed in vivo. These advances will be accompanied by the creation of a growing number of research laboratories around the world dedicated to the study of musical perception and cognition. We seem to be living in a promising moment for this study: each of the disciplines contributing to it is booming. Recently, a convergence of physiological and psychoacoustic approaches has begun to emerge, addressing for the first time the links between the physical and physiological bases of hearing and the more integrated aspects of listening sensation on which musical perception depends. This renewal touches on areas as specific to music as the emotion it arouses, or the benefits it confers on social cohesion. This is what this series of lectures and accompanying seminars has sought to illustrate.