Pitch perception: A dynamical-systems perspective

Two and a half millennia ago Pythagoras initiated the scientific study of t he pitch of sounds; yet our understanding of the mechanisms of pitch percep tion remains incomplete. Physical models of pitch perception try to explain from elementary principles why certain physical characteristics of the sti mulus lead to particular pitch sensations. There are two broad categories o f pitch-perception models: place or spectral models consider that pitch is mainly related to the Fourier spectrum of the stimulus, whereas for periodi city or temporal models its characteristics in the time domain are more imp ortant. Current models from either class are usually computationally intens ive, implementing a series of steps more or less supported by auditory phys iology, However, the brain has to analyze and react in real time to an enor mous amount of information from the ear and other senses. How is all this i nformation efficiently represented and processed in the nervous system? A p roposal of nonlinear and complex systems research is that dynamical attract ors may form the basis of neural information processing. Because the audito ry system is a complex and highly nonlinear dynamical system, it is natural to suppose that dynamical attractors may carry perceptual and functional m eaning. Here we show that this idea, scarcely developed in current pitch mo dels, can be successfully applied to pitch perception.